Vickipedia

excerpts from the 1888 Chambers’s Encyclopedia of Universal Knowledge

August 21, 2007

PALATE

Filed under: biology, medicine, illustrations — Erik @ 2:31 am

PA’LATE, the, forms the roof of the mouth, and consists of two portions, the hard palate in front and the soft palate behind. The framework of the hard palate is formed by the palate process of the superior maxillary bone, and by the horizontal process of the palate bone, and is bounded in front and at the sides by the alvolar arches and gums, and posteriorly it is continuous with the soft palate. It is covered by a dense structure formed by the periosteum and mucous membrane of the mouth, which are closely adherent. Along the middle line is a linear ridge or raphe, on either side of which the mucous membrane is thick, pale, and corrugated, while behind it is thin, of a darker tint, and smooth. This membrane is covered with scaly epithelium, and is furnished with numerous follicles (the palatal glands). The soft palate is a movable fold of mucous membrane enclosing muscular fibres, and suspended from the posterior border of the hard palate so to form an incomplete septum between the mouth and the pharynx; its sides being blended with the pharynx, while its lower border is free. When occupying its usual position (that is to say, when the muscular fibres contained in it are relaxed), its anterior surface is concave; and when its muscles are called into action, as in swallowing a morsel of food, it is raised and made tense, and the food is thus prevented from passing into the posterior nares, and is at the same time directed obliquely backwards and downwards into the pharynx.

Hanging from the middle of its lower border is a small conical pendulous process, the uvula ; and passing outwards from the uvula on each side are two curved folds of mucous membrane containing muscular fibres, and called the arches or pillars of the soft palate. The anterior pillar is continued downwards to the side of the base of the tongue, and is formed by the projection of the palato-glossus muscle. The posterior pillar is larger than the anterior, and runs downwards and backwards to the side of the pharynx. The anterior and posterior pillars are closely united above, but are separated below by an angular interval, in which the tonsil of either side is lodged. The tonsils (amygdalæ) are glandular organs of a rounded form, which vary considerably in size in different individuals. They are composed of an assemblage of mucous follicles, which secrete a thick grayish matter, and open on the surface of the gland by numerous (12 to 15) orifices.

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The space left between the arches of the palate on the two sides is called the isthmus of the fauces. It is bounded above by the free margin of the palate, below by the tongue, and on each side by the pillars of the soft palate and tonsils.

As the upper lip may be fissured through imperfect development (in which case it presents the condition known as hare-lip), so also may there be more or less decided fissure of the palate. In the slightest form of this affection, the uvula merely is fissured, while in extreme cases the cleft extends through both the soft and hard palate as far forward as the lips, and is then often combined with hare-lip. When the fissure is considerable, it materially interferes with the acts of sucking and swallowing, and the infant runs a great risk of being starved; and if the child grows up, its articulation is painfully indistinct. When the fissure is confined to the soft palate, repeated cauterization of the angle of the fissure has been found sufficient to effect a cure by means of the contraction that follows each burn. As a general rule, however, the child is allowed to reach the age of puberty when the operation of staphyloraphy (or suture of the soft parts) is performed—an operation always difficult, and not always successful. For the method of performing it, the reader is referred to the Practical Surgery of Mr. Fergusson. who has introduced several most important modifications into the old operation.

Acute inflammation of the tonsils, popularly known as quinsy, is treated of in a separate article.

Chronic enlargement of the tonsils is very frequent in scrofulous children, and is not rare in scrofulous persons of more advanced age, and may give rise to very considerable inconvenience and distress. It may occasion difficulty in swallowing, confused and inarticulate speech, deafness in various degrees from closure of the eustachian tubes (now often termed throat deafness), and noisy and laborious respiration, especially during sleep; and it may even cause death by suffocation, induced by the entanglement of viscid mucus between the enlarged glands. Iodide of iron (especially in the form of Blancard’s Pills) and cod-liver oil are the medicines upon whose action most reliance should be placed in these cases, while a strong solution of nitrate of silver (a scruple of the salt to an ounce of distilled water), or some preparation of iodine, should be applied once a day to the affected parts. If these measures fail, the tonsils must be more or less removed by the surgeon, either by the knife or scissors, or by a small guillotine specially invented for the purpose.

Enlargement or relaxation of the uvula is not uncommon and gives rise to a constant tickling cough, and to expectoration, by the irritation of the larynx which it occasions. If it will not yield to astringent or stimulating gargles, or to the stronger local applications directed for enlarged tonsils, its extremity must be seized with the forceps, and it must be divided through the middle with a pair of long scissors.

August 13, 2007

ROULETTE

Filed under: recreation, illustrations — Erik @ 11:41 pm

ROULETTE (Fr. ‘a little wheel’), a game of chance which, from the end of last century till the beginning of 1838, reigned supreme over all others in Paris. It continued to be played at German watering-places till 1872, when it ceased in terms of an act gassed four years before. R. is still played at Monaco, in Italy. As much as £8000 a year used to be spent in the papers of Paris alone advertising this game, which is purely one of chance, and is played on a table (see fig.) of an oblong form, covered with green cloth, which has in its center a cavity, of a little more than two feet in diameter, in the shape of a punch-bowl. This cavity, which has several copper bands round its sides at equal distances from each other, has its sides fixed, but the bottom is movable round au axis placed in the center of the cavity; the handle by which motion is communicated being a species of cross or capstan of copper fixed on the upper extremity of the axis. Round the circumference of this movable bottom are 38 holes, painted in black and red alternately, with the first 36 numbers, and a single and double zero, as shown in the figure; and these 38 symbols are also figured at each end of the table in order that the players may place their stakes on the chance they select. Along the margin of the table and at each end of it are painted six words,’ pair, passe, noir, impair, manque, rouge, which will be afterwards explained.

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Those who manage the table and keep the bank are called tailleurs. The game is played as follows: One of the tailleurs puts the movable bottom in motion by turning the cross with his forefinger, and at the same instant throws into the cavity an ivory ball in a direction opposite to the motion of the bottom; the ball makes several revolutions, and at last falls into one of the 38 holes above mentioned, the hole into which it falls determining the gain or loss of the players. A player may stake his money on 1, 2, or any of the 38 numbers (including the zeros), and shows what number or numbers he selects by placing his stake upon them; if he has selected a number or zero corresponding to the one into which the ball falls, he receives from one of the tailleurs 36 times his stake—viz., his stake and 35 times more—if he selected only 1 number, 18 times if 2 numbers, 12 times if 3 numbers, &c. The blank rectangles at the bottom of each of the 3 columns of numbers figured on the table, are for the reception of the stake of that player who selects a column (12 numbers) as his chance, and if the ball enters a hole the number of which is found in his column, he is paid 3 times his stake. Those who prefer staking their money on any of the chances marked1 on the edge of the table, if they win, receive double their stake (their stake and as much more), and under the following circumstances : The ‘pair’ wins when the ball falls into a hole marked by an even number; the ‘ impair,’ if the hole is marked odd; the ‘ manque,’ if the hole is numbered from 1 to 18 inclusive; the ‘ passe,’ if it is numbered from 19 to 36 inclusive; the ‘ rouge,’ if it is colored red; and the ‘ noir,’ if it is colored black.

If the ball should fall into either of the holes marked with the single or the double zero, the stakes of those players who venture upon the 6 chances last described are either equally divided between the bank and the players, or as is more commonly the case, they are ‘ put in prison,’ as it is called, and the succeeding trial determines whether they are to be restored to the players or gained by the bank. Should it so happen that at this trial the ball again falls into one of the two holes (the chance against its occurring is 360 to 1) marked with zeros, then half of the stakes in prison are taken by the bank, and the remainder are ‘ put into the second prison,’ and so on. The tailleurs thus have an advantage over the players in the proportion of 19 to 18. The player who bets upon the numbers labors under a similar disadvantage, for although the two zero-points do not affect him in the same way as the player who stakes upon one of the other 6 chances, still (supposing him to bet upon a single number) as the chances are 37 to 1 against him, he ought to receive 37 times his stake (besides the stake) when he does win, whereas he only receives 35 times that amount, a manifest advantage in favor of the bank in the proportion of 37 to 35.

August 11, 2007

PERFUMERY

Filed under: illustrations, chemistry, art — Erik @ 2:59 am

PERFU’MERY, PE’RFUMES (Fr. perfum, from Lat. fumus, smoke or vapor), delicate fumes or smells. Perfumes are of three distinct classes when derived from plants, and there is a fourth class, which are of animal origin.

CLASS I.—These are the most ancient, and have been in use from the earliest period of which there is record. They consist of the various odoriferous gum-resins, which exude naturally from the trees which yield them; and to increase the produce, the plants are often purposely wounded. The most important are benzoin, olibanum, myrrh, and camphor. No less than 5000 cwt. of these together are annually imported into Britain. Gum-resins form the chief ingredients in ‘ Incense,’ (q. v.), and in Pastilles (q. v.)

CLASS II. are those perfumes which are procured by distillation. As soon as the Greeks and the Romans learned the use of the still, which was an invention imported by them from Egypt, they quickly adapted it to the separation of the odorous principle from the numerous fragrance-bearing plants which are indigenous to Greece and Italy. An essential oil or otto thus procured from orange-flowers bears in commerce to this day the name of Neroly, supposed to be so named after the Emperor Nero. Long before that time, however, fragrant waters were in use in Arabia. Odor-bearing plants contain the fragrant principle in minute glands or sacs; these are found sometimes in the rind of the fruit, as the lemon and orange; in others, it is in the leaves, as sage, mint, and thyme; in wood, as rosewood and sandal-wood; in the bark, as cassia and cinnamon; in seeds, as caraway and nutmeg. These glands or bags of fragrance may be plainly seen in a thin cut stratum of orange-peel; so also in a bay leaf, if it be held up to the sunlight, all the oil cells may be seen like specks. All these fragrant-bearing substances yield by distillation an essential oil peculiar to each; thus is procured oil of patchouly from the leaves of the patchouly plant, Pogostemon patchouly. a native of Burmah; oil of caraway, from the caraway seed; oil of geranium, from the leaves of the Geranium rosa; oil of lemon, from lemon-peel; and a hundred of others of more infinite variety.

The old name for these pure odoriferous principles was Quintessence. Latterly, they have been termed Essential Oils; they are now, in modern scientific works, often termed Ottos, from the Turkish word attar, which is applied to the well-known otto or attar of roses. See oil.

All the various essential oils or ottos are very slightly soluble in water, so that in the process of distillation the water which conies over is always fragrant. Thus, elder water, rose water, orange water, dill water are, as it were, the residue of the distillation for obtaining the several ottos. The process of Distillation (q. v.) is very simple; the fragrant part of the plant is put into the still and covered with water; and when the water is made to boil, the ottos rise along with the steam, are condensed with it in the pipe, and remain floating on the water, from which they are easily separated by decanting. In this way 100 pounds of orange, lemon, or bergamot fruit peel will yield about 10 ounces of the fragrant oil; 100 pounds of cedar wood will give about 15 ounces of oil of cedar; 100 pounds of nutmeg will yield 60 to 70 ounces of oil of nutmeg; 100 pounds of geranium leaves will yield 2 ounces of oil.

Every fragrant substance varies in yield of essential oil. The variety of essential oils is endless; "but there are a certain relationship among odors as among tints. The lemon-like odors are the most numerous, such as verbena, lemon, bergamot, orange, citron, citronella; then the almond-like odors, such as heliotrope, vanilla, violet; then spice odors, cloves, cinnamon, cassia. The whole may be classified into twelve well-defined groups. All these ottos are very soluble in alcohol, in fat, butter, and fixed oils. They also mix with soap, snuff, starch, sugar, chalk, and other bodies, to which they impart their fragrance.

The principal consumption of the various fragrant ottos is for scenting soap. Windsor soap, almond soap, rose soap, and a great variety of others, consist of various soaps made of oil and tallow, perfumed while in a melted state with the several named ottos or mixtures of them.

Though snuff is by no means so popular an article in the reign of Victoria as it was in Anne’s time, yet the increased population, and the extended exports to colonies, cause a production of scented snuff positively greater now than fifty years ago; and it is especially in demand in the fur countries of Northern Canada. There is a large consumption of fragrant essential oils in the manufacture of toilet powders; under the various names of rose powder, violet powder, &c., a mixture of starch and orris, differently scented, is in general demand for drying the skin of infants after the bath.

Precipitated chalk and powdered cuttle-fish bone, being perfumed with otto of roses, powdered myrrh, and camphor, become ‘ Dentrifice.’ The ottos of peppermint, lavender, rose, and others, are extensively used in scenting sweetmeats and lozenges.

More than 200,000 pounds weight of various ottos have been imported into Britain in one year, and valued at over £180,000; to this must be added at least one-third as much again distilled in England. Of the imported articles enumerated, oils of lemon and bergamot, from the Two Sicilies, reached 128,809 pounds, valued at £57,054.

class III.—These are the perfumes proper, such as are used for perfuming handkerchiefs, &c. Contrary to the general belief, nearly all the perfumes derived from flowers are not made by distillation, but by the processes of enfleurage and maceration. Although this mode of obtaining the odors from flowers has certainly been in practice for two centuries in the valley of the Var, in the south of France, it is only by the publication of a recent work* [*Art of Perfumery, by Septimus Piesse, Ph. D., 8vo. 50 cuts. Longman. 4th] that the method has been made generally known. The odors of flowers do not, as a general rule, exist in them as a store or in a gland, but are developed as an exhalation. While the flower breathes it yields fragrance, but kill the flower, and fragrance ceases. It has not been ascertained when the discovery was made of condensing, as it were, the breath of the flower during life; what we know now is, that if a living flower be placed near to grease, animal fat, butter, or oil, these bodies absorb the odor given off by the blossom, and in turn themselves become fragrant. If we spread fresh unsalted butter upon the bottom of two desert-plates, and then fill one of the plates with gathered fragrant blossoms of clematis, covering them over with the second greased plate, we shall find that after 24 hours the grease has become fragrant. The blossoms, though separated from the parent stem, do not die for some time, but live and exhale odor; which is absorbed by the fat. To remove the odor from the fat, the fat must be scraped off the plates and put into alcohol; the odor then leaves the grease and enters into the spirit, which thus becomes ’scent,’ and the grease again becomes odorless.

 

The flower fanners of the Var follow precisely this method on a very large scale, with but a little practical variation, with the following flowers—rose, orange, acacia, violet, jasmine, tuberose, and jonquil. The process is termed enfleurage. In the valley of the Var, there are acres of jasmine, of tuberose, of violets, and the other flowers named; in due season the air is laden with fragrance, the flower harvest is at hand. Women and children gather the blossoms, which they place in little panniers like fishermen’s baskets hung over the shoulders. They are then carried to the laboratory of flowers and weighed. In the laboratory the harvest of flowers has been anticipated. During the previous winter great quantities of grease, lard, and beef-suet have been collected, melted, washed, and clarified. In each laboratory there sire several thousand chassis (sashes), or framed glasses, upon which the grease to be scented is spread, and upon this grease the blossoms are sprinkled or laid. The chasse en -verve is, in fact, 41 frame with a glass in it as near as possible like a window-sash, only that the frame is two inches thicker, so that when one chasse is placed on another, there is a space of four inches between every two glasses, thus allowing space for blossoms. The illustration shows the chasse with grease and flowers upon it (fig. 1), also a pile of the same as in use. The flower blossoms are changed every day, or every other day, as is convenient in regard to the general work of the laboratory or flowering of the plants. The same grease, however, remains in the chasse so long as the particular plant being used yields blossoms. Each time the fresh flowers are put on, the grease is ‘ worked ‘—that is, serrated with a knife—so as to offer a fresh surface of grease to absorb odor. The grease being enfleuree in this way for three weeks or more—in fact, so long as the plants produce blossoms—is at last scraped off the chasse, melted, strained, and poured into tin canisters, and is now fit for exportation. Fat or oil is perfumed with these same flowers by the process of maceration; that is, infusion of the flowers in oil or melted fat. For this end, purified fat is melted in a bain marie, or warm bath, and the fresh blossoms are infused in it for several hours. Fresh flowers being procured, the spent blossoms are strained away, and new flowers added repeatedly, so long as they can be procured.

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The bain marie is used in order to prevent the grease becoming too hot from exposure to the naked tire; so long as the grease is fluid, it is warm enough. Oil does not require to be warmed, but improved results are obtained when it is slightly heated.

Jasmine and tuberose produce best perfumed grease by enfleurage, but rose, orange, and acacia, give more satisfactory products by maceration; while violet and jonquil grease is best obtained by the joint processes—enfleurage followed by maceration. In the engraving a. chasse en fer (2, fig. 1) is shown; this is for enfleurage of oil. In the place of glass, the space is filled with a wire net; on which is laid a molleton, or thick cotton fabric—moleskin, soaked with oil; on this the flowers are laid, just as with solid grease. In due time—that is, after repeated changing the flowers —the oil becomes fragrant, and it is then pressed out of the moleskin cloth. Oil of jasmine, tuberose, &c., are prepared in this way. In order now to obtain the perfume of these flowers in the form used for scenting handkerchiefs, we have only to infuse the scented fat or oil, made by any of the above methods, in strong alcohol.

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In extracting the odor from solid fat it has to be chopped up fine as suet is chopped, put into the spirit, and left to infuse for about a month. In the case of scented oil it has to be repeatedly agitated with the spirit. The result is, that the spirit extracts all the odor, becoming itself ‘ perfume,’ while the grease again becomes odorless; thus is procured the essence of jasmine, essence of orange flowers, essence of violets, and others already named, rose, tuberose, acacia, and jonquil.

It is remarkable that these flowers yield perfumes which, either separate or mixed in various proportions, are the types of nearly all flower odors; thus, when jasmine and orange flowers are blended, the scent produced is like sweet pea; when jasmine and tuberose are mixed, the perfume is that of the hyacinth. Violet and tuberose resemble lily of the valley. All the various bouquets and nosegays, such as ‘ frangipanni,’ ‘white roses,’ ’sweet daphne," are made upon this principle.

The commercial importance of this branch of perfumes may be indicated by the quantity of flowers annually grown in the district of the Var. Flower Harvest: orange blossoms, 1,475,000 lbs.; roses, 530,000 lbs.; jasmine, 100,000 lbs.; violets, 75,000 lbs.; acacia, 45,000 lbs.; geranium, 30,000 lbs.; tuberose, 24.000 lbs. jonquil, 5000 lbs.

class IV. Perfumes of animal origin.—The principal are Musk (q. v.), Ambergris (q. v.), Civet (q. v.), and Castor (q. v.) The aroma of musk is the most universally admired of all perfumes; it freely imparts odor to every body with which it is in contact. Its power to impart odor is such, that polished steel will become fragrant of it if the metal be shut in a box where there is musk, contact not being necessary.

In perfumery manufacture, musk is mixed with other odorous bodies to give permanence to a scent. The usual statement as to the length of time that musk continues to give out odor has been called in question. If fine musk be spread in thin layers upon any surface, and fully exposed to a changing current of air, all fragrance, it is said, will be gone in from six to twelve months.

Civet is exceedingly potent as an odor, and when pure, and smelled at in the bulk of an ounce or so, is utterly insupportable from its nauseousness; in this respect it exceeds musk. When, however, civet is diluted so as to offer but minute quantities to the olfactories, then its perfume is generally admitted; this is so with gas-tar; but the fragrant principle is the same as that breathed by the beautiful narcissus. Castor is in our day almost obsolete as a perfume.

The average importation of musk per annum for a period of five years was 9388 ounces, value £10,688; export 1578 ounces, value £2143; leaving for home-consumption every year 7810 ounces, value £8545. Average importation per annum for a similar period; otto of roses 1117 ounces, value £13,561; vanilla 3525 pounds, value £12,568; ambergris 225 ounces, value £225; civet 355 ounces, value £300; orris root 420 hundredweight.

The works on perfumes are very few; that of Madame Celnart, in the Libraire Roret, is most worthy of notice among the French; a translation of it has been made by Mr. C. Morflt of Philadelphia. In England. The British Perfumer, by C. Lilly (1822), was the only work of the kind published in England prior to the Art of Perfumery by S. Piesse (1855). See also Rimmel’s Book of Perfumes (1875).

August 9, 2007

REAPING

Filed under: economics, engineering, illustrations — Erik @ 6:25 am

REAPING, the act of cutting corn, has been performed from . time immemorial with an instrument called a reaping-hook or sickle. The sickles in use among the ancient Jews, Egyptians, and Chinese appear to have differed very little in form from those employed in Great Britain. The reaping-hook is a curved instrument of about a foot and a half in length, tapering from a breadth of about two inches at the but-end, where it is fixed into a wooden handle. The edge is sometimes serrated, but, as a rule, it has long been made plain and sharp like a knife. In reaping, the harvester takes the corn in his left hand, and then with the hook cuts the stalks as close to the ground as possible; but when a grass crop has been sown down with the grain, the stubble is often left rather longer, in order to preserve the young grass The corn is placed handful by handful in a band usually made of the corn, and when as much has been cut as will form a sheaf, it is tied up by the ‘ bandster.’ The most expert reapers slash down the corn with the hook in the right hand, using the left merely to keep the corn from falling, until sufficient to make a sheaf has been cut, when the reaper places his hook under the corn, and supporting it with his left arm, deposits it all at once in the band. A bandster (one to every three or four reapers) binds the grain, and sets it up in stocks of generally 12 sheaves. It was surprising to see women of sixty years and upwards, handling the ‘ hook ‘ with great dexterity, accomplishing their 20 and sometimes 24 stocks of 12 sheaves each per day. After such a day’s work, these women appeared much fatigued, but a night’s rest seemed to set them on foot, vigorous as ever. They divested themselves of much of their clothing, and really worked hard for their money.

In the principal corn-growing districts of Scotland, a great proportion of the reaping by hand was at one time done by laborers from Ireland, who undertook the work at from 8s. to 15s. per acre, with board and lodging in addition. Their fare was of the simplest kind—consisting in the majority of cases, of porridge morning and evening, and bread and beer for dinner; their lodging at night was the barn or some outhouse, the farmer providing coarse blankets for covering. The quantity of porridge consumed at each meal by those people was sometimes astonishing—no less, as has been proved by actual weighing, than 5 lbs., with 1 ½ lbs. of milk besides. In England, most of the corn was cut by piecework, at prices varying from 10s. to 18s. per acre. On the stronger lands of the midland and southern counties, the stubble is some-times left knee-high, and afterwards at leisure cut by the scythe, or with a long hook, at a cost of 2s. per acre. In Yorkshire, Derbyshire, Oxfordshire, and on many of the lighter soils in other counties, the operation of fagging or hacking, to be afterwards noticed, was preferred as being more expeditious than reaping. A good hand cut down from one-third to one-half of an acre of wheat, and often consumed, during his long day’s labor, two gallons of good ale.

The scythe in some counties, more than thirty years ago, was preferred to the sickle. The most common varieties were: the Hainault scythe—an importation from Belgium—the cradle scythe, and the common scythe fitted with a cradle. The Hainault scythe consists of a blade about 2 feet 3 inches long, having a handle 14 inches long. This the mower holds in his right hand, while in his left he carries a hook, with a handle of about equal length. ‘The reaping,’ says the late Mr. Henry Stephens, in his Book of the Farm, ‘is done by pressing the back of the hook with the left hand against the standing corn, in the direction of the wind, and by cutting with the scythe close to the ground against the standing corn with a free swing of the right arm,’ the hook keeping the cut corn from falling until a sufficient quantity to form a sheaf has been cut. This operation was practised in many parts of England, and especially on the lighter soils, under the name of fagging or hacking, the reaper sometimes using in his left band. instead of the hook, a stout crooked stick from 2 1/2 to 3 feet long. Beans and oats were the crops most generally fagged.

The cradle scythe is composed of a blade about 3 1/2 feet long, attached to a principal helve or sned about 4 feet long, into which another helve of about 2 1/2 feet in length is tenoned, thus making two handles. The cradle or bow is a piece of wood joined to the heel of the blade, into which are inserted three or four wooden teeth, in a line with the blade, the object of which is to secure the grain being laid evenly in one direction. As skill at the working of the scythe, however, increased, the cradle or bow was discarded in many cases. By the scythe, corn can be cut at a rather less cost per acre than with the hook; but the work is not so neatly done. As nice a stubble will be left by a good hand with the scythe, and often nicer than by the hook, but the sheaves are not, as a rule, so tidy after the scythe, though they will stack rather earlier. Of a fair working crop, an adept at the scythe would cut 2 or 2 1/4 acres per diem. The average area cut per day with the scythe does not exceed 1 1/2 acres. In fact, if the crop is heavy, that extent is a very hard day’s work. Those who contract for cutting the crops by the scythe, obtain the services of the best men, and thus generally get about 2 acres per day reaped, and reaped very well too. In the midland and southern counties, of England, the scythe, long in general use, was of larger size, and had only one long shaft, on which were fixed two handles. In Bedfordshire, Hertfordshire, and some of the eastern counties, the whole of the cutting, until the introduction of reaping-machines, was done by these scythes. The harvest operations then, from the cutting of the crop to the thatching of the ricks, cost from 18s. to 25s. per acre.

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The process of reaping with either the sickle or the scythe is, however, both tedious and expensive; and hence, during the last three-quarters of a century, many attempts have been made to accomplish the work by machinery—attempts which, in the course of the last twenty years, have been crowned with complete success ‘ Reaping by machinery, however, is no modern invention. Pliny the elder, who was born in the 1st c. of the Christian era, found a reaping-machine in Gaul. He says : ‘ In the extensive fields in the lowlands of Gaul, vans of large size, with projecting teeth on the edge, are driven on two wheels through the standing corn by an ox yoked in a reverse position. In this manner the ears are torn off, and fall into the van.’ Palladius, about four centuries later, found a similar appliance for reaping corn in Gaul. He gives a more detailed but similar description of the machine. The annexed cut, copied from Mr. Woodcroft’s Appendix to the Specifications of English Patents for Reaping-machines, represents what is conceived, from the descriptions, to have been the form of this ancient reaper.

In modern times, the idea of a mechanical reaper appears to have originated with a Mr. Capel Lloft, who, in 1785, suggested a machine something after the pattern of the ancient one above described. Between that time and the Great Exhibition of 1851, in London, from which the general use of mechanical reapers may be said to date, the patents taken out for reaping-machines were very numerous. Among the most promising of these may be mentioned those of Mr. Gladstone of Castle-Douglas; Mr. Smith of Deanston; Mr. Kerr, Edinburgh; Mr. Scott of Ormiston; Mr. Dobbs, an actor in Birmingham; Mr. Mann of Raby, near Wigton; and the late Rev. Patrick Bell of Carmylie, Scotland. In 1826, Mr. Bell constructed an efficient and simple machine, which long continued in use, and several features of which are observable in the reapers of the present day. The inventor of this, the first machine of the kind in Scotland, received a public testimonial from agriculturists, in consideration of the services he thus rendered to agriculture. In America Mr. Hussey and Mr. M’Cormick took out patents for reaping-machines of superior character in 1833 and 1834 respectively.

The movements of the cutters of these machines were various. A few were advancing only, some sidelong and advancing, others reciprocating and advancing, a large number continuous and advancing, and others continuous and alternate. The reciprocating and advancing motion is that now employed on the machines in use. The principal difference in the machines now so largely used for cutting corn is in the form and character of the cutters, and in the mode of delivering the grain after it is cut.

The cutting-knives are of two kinds—one, obtuse-angled and serrated; the other, acute-angled and for the most part plain. Both are attached to a bar, and are made to-work through another bar of iron fitted with hollow fingers, called guard-fingers, which, projecting forwards, catch the standing corn, and retain it firmly until it is cut. The serrated knife saws through it; the plain knife clips it, as it were; the finger-guard forming the fixed blade of the scissors.

The delivery of the sheaves is effected either by manual or mechanical labor; but the vast proportion of the machines in use are what are termed manual delivery-reapers. The delivery of the sheaves by manual labor is now almost at the back of the machine, the side delivery being generally abandoned, unless in the self-deliveries. In delivering the grain, a man, with a short-handled rake in his hand, sits upon the machine almost opposite the cutting apparatus. With this he inclines the grain towards the knife; and when sufficient to make a sheave has been cut, he rakes it off the platform upon the machine, on to which it has fallen, and deposits it on the ground. The cut subjoined will illustrate the method of raking off. In making a neat and squarely-formed sheaf, the raker is greatly assisted by a hinge in the platform, which enables him, by pressure of the foot, to tip the board over, so as to let the corn slide gently down.

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With the back-delivery, the sheaves must be tied up and removed out of the way of the machine before it comes round again. Such a reaper, therefore, always requires a full supply of hands to attend upon it. But it is the best for all that. It does require a skilful, careful man to ‘ tilt,’ but the fact that the course has to be kept clear for the horses every round, spurs the laborers, who thus do more work than they would otherwise accomplish. Besides, it is a very doubtful advantage to be enabled to slash down the crops irrespective of the gathering capacities. Moreover, with the self-deliveries, it is the distance gone over, and not the quantity of crops collected, that regulates the size of the sheaf. With uneven crops, this is an inconvenience. Sheaves of different sizes are very troublesome in the stock. They will not stand well, and in stacking it is difficult to keep uniformity in building. Large and small sized sheaves are not equally dried, and are not ready for stacking at the same time. Eight people ‘ lifting’ after the manual-reaper will do as much work as nine following the self-delivery, so that the saving of a man’s labor claimed by the self-delivery is doubtful. The sheaves are rather better formed by the manual machine than by the self-delivery. Each kind, has, however, and will likely continue to have its advocates, though the preponderance is in favor of the manual.

The mechanical or self-delivery machines, as they are generally called, are of two kinds—one lays the cut corn in swaths, the other deposits it in sheaves. The latter is decidedly the best and most fashionable of the two.

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The automaton sheaf-deliverers best known to the public are those of Samuelson of Banbury; Hornsby and Son; Burgess and Key; Brigham and Bickerton, Berwick; Howard and Co., Bedford. We give a description of Samuelson’s sheaf-deliverer (largely used in Great Britain), which will be made plain by the accompanying cut. The self-delivering machinery consists of a series of four rakes—two toothed, and two plain—attached to an upright shaft, in such manner as to admit of a free ascending, descending, and horizontal motion. The two toothless rakes, or ‘ dummies,’ are shorter in the arms by six inches than the other two, and are merely employed to incline the grain towards the cutter. The platform upon which the grain fails after it is cut is of quadrant shape, and is surrounded, on the outer edge, by a rim of about a foot deep. The side of the earn next the platform is bent or depressed, so that the rakes on reaching this point, make a sudden fall, or eccentric motion, thus assuming the horizontal attitude necessary to sweep over the platform on the level. The rakes are adjusted so as to lay the sheaves about 12 feet apart, to the side, and out of the way of the horses. This machine has a, double-throw knife—an arrangement which reduces the driving speed, and consequently the wear and tear of the machinery.

In M’Cormick’s automatic delivery-machine, a rake is so used that ‘during one part of the revolution of the gathering-reel, it acts as one of the vanes of the reel in bending the standing corn to the cutting-blades. When the rake reaches the cutting-blades in front of the platform, it ceases to revolve around the reel-shaft (which continues its rotary motion), and is made to move horizontally upon a vertical hinge, to which one end is attached (the points of the teeth being near the surface of the platform), sweeping the cut corn off at the side, and depositing it on the ground in sheaves ready for the binder.’ The Messrs. Brigham and Bickerton’s improved machine has a deep upright board of sheet-iron to keep the corn on the platform. Iron rods on these sheets separate the corn. This firm has thrown off two branches lately. The first offshoot was Messrs. Lillie and Elder, and the last was Bickerton and Co. The three firms make good serviceable reapers. Howard and Hornsby’s reapers are substantially and simply constructed, embracing slight improvements every other year, formed on experience. Prices range from £20 to £35.

The makers of manual delivery-machines are numerous, including in a prominent degree Kemp, Murray, and Nicholson, Stirling; Jack and Sons, Maybole; Harrison, Macgregor, & Co.; Picksley, Sims & Co.; Ransome, Sims and Head, Ipswich; Sam-nelson & Co., Banbury; J. and F. Howard, Bedford; and many others of fame. The manual delivery-machines of the first named firm are very popular, strong and ingeniously manufactured, while those of the Maybole firm are not quite so strong, but work with great ease and tastefulness. Carefully handled, the manual delivery-reaper will take up laid and twisted crops admirably. Indeed, all the reapers nowadays, perfected as they are year by year, now do their work remarkably well, leaving a beautiful stubble and a nice sheaf. The sheaves from the reaper, however, are not so easily dried for the stackyard as those from the scythe, but they defend rain better, and are altogether preferable. The number of reapers now in use in Great Britain is enormous, and is growing rapidly every year. They are a most decided improvement. Indeed, they are one of the most valuable introductions that have been made in rural agriculture in this country. At almost every farm of ordinary or even comparatively small dimensions, there is a reaper, and three or four engaged on the larger holdings. The cost of the manual delivery ranges from £18 to £30.

The cost of reaping by machinery is much less than either by scythe or sickle. Mr. Wilson of Woodhorn, Morpeth, found that the cutting of wheat with the sickle (binding and stocking included) cost him from 11s. to 15s. per acre, and with the scythe 8s., whilst with the machine it only cost him 5s. 9d., exclusive of wear and tear. From data supplied by a large number of their customers, Messrs. Samuelson & Co. make out that the saving by mechanical over hand labor is, as compared with reaping, 4s. per 1 acre, and with mowing, Is. 9d. per acre; and most farmers who have tried reaping-machines set down the saving at from 20 to 30 per cent. Besides, there is about a like economy in time, which is of immense importance in a variable climate like that of Great Britain.—See Woodcroft’s Appendix to Patents for Reaping-machines; Mr. Jacob Wilson’s ‘ Essay on Reaping-machines,’ in Transactions of Highland Society for January 1864; Book of Farm Implements, and Book of the Farm, by Henry Stephens; J. C. Morton’s Cyclopaedia of Agriculture.

February 17, 2007

TASTE, ORGAN AND SENSE OF

Filed under: biology, illustrations, science — Erik @ 2:30 am

TASTE, organ and sense of. The principal seat of the sense of taste is the mucous membrane of the tongue, in which dissection reveals a cutis or chorion, a papillary structure, and an epithelium. Of the cutis, it is sufficient to remark that it is tough, but thinner and less dense than in most parts of the cutaneous surface, and that it receives the insertions of the intrinsic muscles of the tongue, which will be described when we treat of that organ generally. The papillary structure differs from that of the skin in not being concealed under the epithelium, but in projecting from the surface like the villi of the digestive canal, and it thus gives to the tongue its well-known roughness. The Epithelium (q. v.) is of the scaly variety, as on the skin, but is much thinner on the tongue than on the skin. It is most dense about the middle of the upper surface of the tongue, and it is here that, in disordered digestion, there is the chief accumulation of fur, which in reality is simply a depraved and over-abundant formation of epithelium. The papillæ on the surface of the tongue are either simple or compound. The former, which closely resemble those on the skin, are scattered over the whole surface of the tongue in parts where the others do not exist, and they likewise participate in the formation of the compound papillæ, which, from their forms, are respectively termed (1) the circumvallate or calyciform, (2) the fungiform, and (3) the conical or filiform.

The circumvallate papillæ are not more than eight or ten in number, and are situated in the form of a V at the base of the tongue. Their function seems to be to secrete mucus, as well as to take part in the act of tasting. They consist of ‘ a central flattened projection of the mucous membrane of a circular figure, and from 1/20th to 1/12th of an inch wide, surrounded by a tumid ring of about the same elevation.’—Todd and Bowman, Physiological Anatomy and Physiology of Man, 3d ed. vol. i. p. 437. They are shown in the figure of the surface of the tongue given in the article on that organ.

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The fungiform papillæ are scattered over the surface in front of the circumvallate papillæ, and about the sides and apex. They are usually narrower at the base than at the apex, where they are about 1/30th of an inch in diameter. They are covered with simple or secondary papillæ, and their investing epithelium is so thin that the blood circulating in them gives them a red color, which is not seen in the conical papillæ amongst which

taste2.jpg

they are distributed. They contain nerves terminating in loops. The shape of the conical or filiform papillæ is indicated by their names; and even if they take little part in the sense of taste directly, it is convenient to describe them here. Their average length is about 1/10th of an inch. The structure of these papillæ will be better understood from the accompanying diagrams than from any verbal description. They terminate in long pointed processes, which are bathed by the mucus of the mouth, and are capable of moving in any direction, although they are generally inclined backwards.

Some of the stiffer of these epithelial processes enclose minute hairs, of which several forms are depicted by Messrs. Todd and Bowman, from whose Physiological Anatomy all the figures in this article are borrowed. These authors surmise, on structural grounds, that the filiform papillæ ‘ can scarcely share in the reception of impressions which depend on the contact of the sapid material with the papillary tissue.

taste3.jpg

The comparative thickness of their protective covering, the stiffness and brushlike arrangement of their filamentary productions, their greater development in that portion of the dorsum of the tongue which is chiefly employed in the movements of mastication, all evince the subservience of these papillæ to the latter function rather than to that of taste; and it is evident that their isolation and partial mobility on one another must render the delicate touch with which they are endowed more available in directing the muscular actions of the organ. The almost manual dexterity of the tongue in dealing with minute particles of food is probably provided for, as far as sensibility conduces to it, in the structure and arrangement of these papillæ.’—Phys. Anat. and Phys. of Man, vol. i. p. 441. Notwithstanding the difference in their outward form and mode of arrangement, the simple papillæ, which have been detected by Todd and Bowman as scattered over the whole dorsum of the tongue (although concealed under the common sheet of epithelium), and those clothing the circumvallate and fungiform papillæ, do not seem to present any structural difference; and their epithelium, which is very thin, readily permits the transudation of sapid substances dissolved in the mucus of the mouth. With regard to the use of the singular configuration of the circumvallate and fungiform papillæ, ‘ it may be conjectured that the fissures and recesses about their bases are designed to arrest on their passage small portions of the fluids in which the sapid materials are dissolved, and thus to detain them in contact with the most sensitive parts of the gustatory membrane.’ —Op. cit-, p. 441.

There has been much discussion regarding the precise seat of the sense of taste and the true nerves of taste. Although the surface of the tongue is the special seat of gustative sensibility in man, the sense of taste is by no means restricted to that organ, being diffused, in a less degree, over the soft palate, the arches of the palate, and the fauces. Moreover, the gustative sensibility varies on different parts of the surface of the tongue. It is generally allowed that acute taste ‘ resides at the base of the tongue, over a region of which the circumvallate papillæ may be taken as the center, and also on the sides near the base. These parts are supplied solely by the glossal twigs of the glosso-pharyngeal nerves. Some writers, amongst whom are Valentin and Wagner, believe the middle and anterior parts of the dorsum of the tongue to be usually incapable of appreciating flavor; while numerous others hold the contrary opinion, with which our own careful and repeated experiments, on other persons as well as ourselves, quite accord. Sour, sweet, and bitter substances applied to the sides, and especially to the tip of the protruded tongue, we find to be at once distinguished; though, when placed on the middle of the dorsal region, they make little or no impression till pressed against the roof of the mouth. This region of the tongue is supplied almost solely by the lingual branch of the fifth nerve. We conclude generally, with regard to the tongue, that the whole dorsal surface possesses taste, but especially the circumferential parts, viz., the base, sides, and apex.’—Op. cit., pp. 442, 443. The investigations of Messrs. Todd and Bowman further show that the soft palate and its arches are endowed with taste in some persons, but not universally, while they got no evidence in any case of gustative sensibility on the pharynx, gums, or elsewhere. The soft palate and its arches are supplied by palatine brandies from Meckel’s ganglion, and sparingly by the glosso-pharyngeal nerves. Prom (1) the evidence afforded by the anatomical distribution of the nerves to parts enjoying the sense of taste, (2) the evidence of experiments, in which the various nerves of the tongue were divided, and (3) the evidence afforded by disease, it may be safely inferred that the glosso-pharyngeal and the lingual branches of the fifth pair of nerves respectively participate in the sense of taste; and there is also reason to attribute a share to the palatine branches of the fifth.

Impressions of taste may be produced by a mechanical or chemical excitement of the gustatory nerves. A quick light tap of the finger on the tip of the tongue causes a taste, sometimes acid, sometimes saline, which lasts for several seconds; and galvanism acts similarly. If the surface of the tongue, near the root, be touched with a clean dry glass rod, or a drop of distilled water be placed upon it, a slightly bitterish sensation is produced; and if the pressure be continued, a feeling of nausea ensues. If a small current of cold air be directed against the tongue, it excites a cool saline taste like that of saltpetre. From the experiments of E. H. Weber, it appears that one of the conditions requisite fertile due exercise of the sense of taste is a temperature not departing far on either side from the natural standard. Thus, if the tongue be immersed for a minute in water at a temperature of 125°, or in iced water, the taste of sugar, &c., is no longer perceived. In order that sapid bodies should cause taste, it is necessary that they should be dissolved, and made to permeate the tissue of the papillæ, so as to come in contact with their nerves. This is proved by the two following facts: 1st, that every substance, whether solid, fluid, or gaseous, which possesses a distinct taste, is more or less soluble in the fluids of the mouth, while substances which are perfectly insoluble are only recognized by the sense of touch; and 2d, that if the most sapid substance be applied in a dry state to a dried part of the surface of the tongue, no sensation of taste is excited. Bitters and acids appear to be the most sapid bodies, since they may be diluted to a greater extent than any other known substances without ceasing to excite sensations of taste. Thus, according to Valentin, 1 part of extract of aloes, or of sulphuric acid, in 900,000 of water, and even 1 part of sulphate of quinia in 1,000,000 parts of water, may, with ease, be distinguished from perfectly pure water.

‘ The contact of a sapid substance,’ says Dr. Carpenter, ‘much more readily excites a gustative sensation when it is made to press upon the papillæ, or is moved over them. Thus there are some substances whose taste is not perceived when they are simply applied to the central part of the dorsum of the tongue, but of whose presence we are at once cognizant by pressing the tongue against the roof of the mouth. The full flavor of a sapid substance, again, is more readily perceived when it is rubbed on any part of the tongue, than when it is simply brought in contact with it, or pressed against it. Even when liquids are received into the month, their taste is most completely discriminated by causing them to move over the gustative surface : thus, the ‘ wine-taster’ takes a small quantity of the liquor in his mouth, carries it rapidly over every part of its lining membrane, and then ejects it."—Principles of Human Physiology, 6th ed. p. 621. Most sapid substances affect the nerves of smell to a greater or less degree, as they pass down the throat; and it is this compound of taste and smell that constitutes flavor. It is a common habit to hold a child’s nose when he is taking a nauseous draught, with the view, as is supposed, of deadening the taste. The efficacy of the process depends upon the exclusion of smell, and the reduction of the flavor of the medicine to its mere taste. The agreeable sensation produced by sipping good wine is due to what is termed its bouquet, or, in other words, to its flavor, or combined taste and smell. Some substances leave a taste in the mouth very different from that which they first produced. This after-taste is usually bitter; but in the case of one of the most bitter substances known, namely, tannin, it is sweet. This connection seems, in a degree, to correspond to the complementary colors in vision.

February 8, 2007

THEODOLITE

Filed under: geography, engineering, illustrations — Erik @ 3:46 am

THEO’DOLITE (Gr. theao, I see, dolichos, long), an instrument much employed in land-surveying for the measurement of angles horizontal and vertical, is neither more or less than an altitude and azimuth instrument, proportioned and constructed so as to be conveniently portable. Like all instruments in very general use. the variations in its construction are almost numberless; but its main characteristics continue unaltered in all forms. It consists essentially of two concentric circular plates of copper, brass, or other material (the upper plate, or upper horizontal, either being smaller, and let into the lower, or lower horizontal, or the rim of the lower raised round the outside of the upper), moving round a common axis, which, being double, admits of one plate moving independently of the other. Upon the upper horizontal rise two supports, bearing a cross bar, which is the axis of a vertical circle moving in a plane at right angles to the former. This latter circle either has a telescope fixed concentric with itself, or a semicircle is substituted for the circle, and the telescope is laid above, and parallel to its diameter. The circles, as their names denote, are employed in the measurement of horizontal and vertical angles. For these purposes, the outer of the horizontal circles is graduated, and the inner carries the index-point and the Verniers (q. v.); the vertical circle is also graduated, and the graduations are generally read off by an index-point and vernier firmly attached to the supports. The upper horizontal is furnished with two levels placed at right angles to each other for purposes of adjustment, and has a compass-box let into it at its center. The stand consists of a circular plate supported on three legs, and connected with the lower horizontal by means of a ball-and-socket joint; the horizontal adjustment of the instrument being effected by means of three or four (the latter number is the better) upright screws placed at equal distances between the plates.

theodolite.jpg

The telescope is so fixed as to be reversible, and the adjustments are in great part similar to those of other telescopic instruments, but are too numerous and minute to be here detailed. Both horizontal plates being made, by means of the screws and levels, truly level, the telescope is pointed at one object, and the horizontal angles read off; it is then turned to another object and the readings-off from the graduated circle again performed; and by the difference of the readings, the angular horizontal deviation is given; and when vertical angles are required, the readings are taken from the vertical circle in a similar manner.

September 20, 2006

BLASTING

Filed under: engineering, illustrations — Erik @ 1:47 am

BLASTING. Before gunpowder was invented, the separation of masses of stone from their native rock could only be effected by means of the hammer and wedge, or by the still slower method of fire and water. In soft and stratified rock, wedges are still used for quarrying stones for building purposes; but in hard rock, or where regularity of fracture is no object, gunpowder is ordinarily employed. There are two kinds of B.�first, the small shot system; and second, that of large blasts or ‘mines.’

The small-shot system consists of boring holes into the rock, of from one to six inches in diameter, and of various depths, according to circumstances. In hard rock, this is done by a steel-pointed drill, struck by a hammer, and turned partly round after each blow, to make the hole cylindrical. The addition of a little water serves to preserve the temper of the boring tool, and makes the rock more easy to cut. In soft rock, whenever the hole is to be vertical, a ‘ jumper’ is used; this is a weighted drill, which acts, merely by its own weight, when let fall from about a foot in height. The powdered stone is removed at intervals by a ’scraper.’ The rate of progress varies, of course, with the hardness of the rock.

At Holyhead, the average work done by three men in hard: quartz rock, with 11/2 inch drills, is 14 inches in depth per hour; one man holding the drill, and two striking. After the hole is bored, it is cleaned out, and the powder poured down. A wad of dry turf or hay is put over the charge, and the rest of the hole ‘ tamped,’ or filled with broken stone, clay, or sand. The shot is fired by a length of Bickford’s patent fuse. When it is desirable to prevent the stones from flying about, when the shot is fired, a shield of boiler-plate, or of brushwood weighted, may be laid over the hole.

Small shots may be fired, even under water, by enclosing the charge in a tin case, with a tube of powder reaching to the surface; or in a canvas bag, well tarred, tied at the neck round a length of Bickford’s fuse, which burns under water. The charge is inserted in the drill-hole; and the weight of the superincumbent water acts as tamping.

In removing the wall between the old and new Shadwell basins of the London Docks, shots were fired under water within a few yards of vessels lying in the basin, by using moderate charges, and by keeping a raft of timber floating over the hole, as a shield to prevent anything flying upwards.

The voltaic battery has been used for firing shots, chiefly under water, since 1839, in which year it was employed at the wreck of the Royal George and at the Skerryvore Light-house.

When a large mass of rook has to be removed at once, or where a steady supply has to be daily furnished of irregularly broken stone, for breakwater or other purposes, recourse must be had to large blasts, or ‘mines.’ The greatest isolated example of this kind of blasting was the overthrow, in 1843, of the Rounddown cliff at Dover, by 18,500 lbs. of powder, in three separate charges, fired simultaneously by voltaic electricity. But by far the grandest system of B. by mines is to be seen at quarries for supplying stone to the Breakwater at Holyhead, where small shots having been found inadequate, large mines were introduced in 1850. These large blasts are of two kinds�’shafts’ sunk from the top of the rock; and ‘headings,’ or galleries driven in from the face.

The shaft-holes are 6 feet long by 4 feet wide, of various depths, according to the height of the rock, but seldom much exceeding 60 feet. The deal-box, with, the charge of powder, p, is placed in a chamber cut at one side of the shaft, so that the tamping may not be in the direct upward line of fire. The tamping consists of the stone and debris which have come out of the shaft; and the wires from the battery are protected from injury by being laid in a groove cut in a batten placed up one angle of the shaft.

It is evident that the same point, p, in the rock may be reached as well by a heading or gallery driven in from the face of the rock, as by a shaft from the top, and often by a shorter route. Headings are made 5 feet high by 3 feet 6 inches wide, and are driven, if possible, along a natural joint in the rock. The direction of the gallery is changed and sunk at parts, to prevent the tamping from being blown out. Four men can, on the average, drive 5 feet run of heading per week; but cannot sink above 3 or 4 feet of shaft, which has a greater sectional area, and is more inconvenient to work in.

The charge of powder may be divided and placed in two or more separate chambers, as p, and p; and� it is� better thus to spread a heavy charge over a length of face, than to have it in one spot, at a greater distance from the face than about 30 feet. The charges for these mines vary from 600 lbs. to 13,000, and even more, pounds of powder; and the produce is from 2 to 6 tons of stone to the pound of powder, according to the density of the rock and the position of the mine.

Besides the quarrying of stone, B. is used for military objects, or where total destruction is aimed at, and an excess of powder is little or no objection.

Of late years great improvements have been effected in the production and application of explosive agents other than gunpowder, which latter, until lately, may be said to have been exclusively used for the purpose of blasting. Nitroglycerine (q. v.) and gun cotton (q. v.) were discovered within two years of each other; but while gun cotton was immediately applied to industrial purposes, nitroglycerine was destined to remain a chemical curiosity for about 16 years.

Dynamite is a preparation of nitroglycerine and porous earth, in the form of a pasty mass, which, without materially impairing its explosive properties, has the effect of rendering it perfectly safe to handle.

One of the most celebrated applications of boring and blasting to modern engineering was the driving of the Mont Cenis tunnel. See tunnel.

September 19, 2006

BLAST FURNACE

Filed under: engineering, illustrations — Erik @ 7:28 am

BLAST FU’RNACE. Many costly experiments have been tried of late years in order to determine, along with other related questions, the best form of the blast furnace in which iron is smelted. Which is the most serviceable form is as yet a very much disputed point, but according to the published accounts, furnaces of the unusual height of 80 to 100 feet give, as a rule, the best results. There are two types of blast furnaces, irrespective of differences in their forms, as regards the way in which they are constructed. Some are built with thick walls, either entirely of brick or of brick and stone, hooped with iron, forming massive towers. Others, again, are formed of comparatively thin brick walls, and depend for their strength on an outer malleable iron casing, in which case they are called cupola furnaces. The furnace A, in fig. 1, article IRON, is an example of the former, and the annexed figure represents one of the latter kind.

The various parts of the furnace are distinguished as follow: A is the shaft or body, generally either in the form of a cone or cylinder, or somewhat barrel-shaped, in which ease, the portion marked B is not distinguishable from the shaft. B. is called the boshes, and is the part of the furnace which, from the high heat to which it is exposed, usually gives way first. H is the hearth, and C is the tunnel-head, which, however, is usually wanting, when the mouth is closed by a bell and cone to save the gases generated in the furnace. P is the charging platform, and Q,Q, the opening through which the ore, fuel, &c., are fed. These materials are brought to the platform by hoists, inclines, or level gangways, according to the situation of the furnace. Just below the boshes there are four or five openings in the circumference for the tuyeres t, and another for the arrangements required for tapping the furnace As respects the latter, a is called the tymp-arch, immediately below which is placed the tymp itself, consisting of a rectangular iron box containing water in a coiled pipe. The hearth is prolonged in the direction of the dam-plate d, and the space between it and the tymp is filled up with sand or clay, in which there is a channel for the escape of slag. In the damp-plate is placed the tapping-hole, i, through which the molten iron is run off. The pipe at p conveys the blast, produced by a powerful blowing-engine, and heated to between 600� and 1400� F. The B. F. may tee used with the Siemens Gas Furnace. See IRON and GLASS.

August 21, 2006

AMBULANCE

Filed under: medicine, illustrations, military — Erik @ 8:14 am

A’MBULANCE, a military term which is somewhat differently applied in different countries. In France, an A. is a portable hospital, one of which is attached to every division of an army in the field, and provided with all the requisites for the medical succor of sick or wounded troops. Such an A. is stationed at some spot removed from immediate danger; and soldiers are sedulously employed after a battle in seeking out those who have fallen, and conveying them to the A. Baron Larrey, during the great wars of the First Napoleon, brought this department of medical business to a high degree of efficiency, and set an example to the rest of Europe. When England engaged in war with Russia in 1854, the A. arrangements, like many others relating to the army, were in a very imperfect state. In the English army, A., strictly speaking, means a field hospital with all its wagons, litters, tents, cooking canteen, &c-; but sometimes the name is applied to a four-wheeled wagon or a two-wheeled cart fitted up for the reception of wounded men. When Lord Raglan was about to be sent out with the army, Dr. Guthrie, President of the College of Surgeons, devised a new form of A. cart; while Dr. Andrew Smith, Director-general of the Army and Ordnance Medical Department, invented a new A. wagon.


Annexed is a figure of Dr. Guthrie’s A. cart. The badly wounded were laid on it at full length, while those slightly hurt sat in front and rear, and on the sides. A stretcher is slung from the top for the accommodation of the former. The back-board is let down for cases requiring amputation. The hospital chests are lashed underneath. Many of Smith’s A. wagons and of Guthrie’s A. carts were at once made and sent out to the East; but they were not at the proper place when most wanted. After the battle of the Alma, the English were almost entirely destitute of means for conveying their wounded down to the beach; but the French had for this purpose a large number of camlets, suggested to them by their experience in Algeria. Each of these consists of two easy-chairs, slung in panniers across the back of a mule; and it is accordingly available along tracks where no wheel-carriage could pass. These cacolets have since been adopted in the English army, as well as improved, hand-litters, wheeled-litters or barrows, and ambulance wagons on a more modern model than those of Smith and Guthrie, but having the same general character. The American War, the wars of 1866 and 1870, and above all, the growth of volunteer aid societies under the influence of the Geneva Convention of 1866 (which gave to the wounded and their attendants the privileges of neutrality), have largely developed the ambulance equipments of every European army. Every international exhibition now contains an immense number of designs for the safe transport of the wounded. The most remarkable step taken in this direction has been the organization of railway ambulances. Trains of carriages either built for the purpose, or adapted from the ordinary rolling stock, can now be fitted up as moving hospitals, with their staff of surgeons and attendants; and by means of these railway ambulances the wounded can be safely and rapidly removed from the encumbered field hospitals to the permanent hospitals of the great cities of their own country. All the fittings for thus adapting railway trains to hospital purposes are now kept permanently m store in many of the countries of the continent.

August 7, 2006

AMANITA

Filed under: biology, illustrations — Erik @ 3:18 pm

AMANI’TA, a genus of Fungi, nearly allied to Agaricus, but bursting from a volva. A. muscaria, which is pretty common in woods, especially of fir and beech, in Britain, is one of the most dangerous fungi. It is sometimes called FLY AGARIC, being used in Sweden and other countries to kill flies and bugs, for which purpose it is steeped in milk. The pileus or cap is of an orange-red color, with white warts, the gills white, and the stem bulbous. It grows to a considerable size. Notwithstanding its very poisonous nature, it is used by the Kamchatkadales to induce intoxication, and it imparts an intoxicating property to the urine of those who swallow it, of which they or others often avail themselves, when abundance of the fungus is not at hand.

August 2, 2006

ARTIFICIAL LIMBS

Filed under: biology, engineering, illustrations — Erik @ 9:46 am

ARTIFI’CIAL LIMBS. With the exception of the celebrated’ artificial hand of the German knight, G�tz von Berlichingen* [* The iron hand of this knight, who has been immortalized by Goethe, it preserved at Jaxthausen, near Heilbronn, and a duplicate of it is in the Schloss Erbach, in the Odenwald. It is stated in Scott’s Harder Antiquities, vol. ii,p. 206, that the family of Clephane of Carslogie ‘have been in possession from time immemorial of a hand made in the exact representation of that of a man, curiously formed of steel,’ which was conferred by one of the kings of Scotland on a laird of Carslogie, who had lost his hand in the service of his country.�See Notes and Queries for July 17, 1867, p. 35.] �who flourished in the early part of the 16th c. (1513), and who was named The Iron-handed � which weighed 3 pounds, was so constructed as to grasp a sword or lance, and was invented by a mechanic of Nuremberg, our knowledge of artificial limbs dates from the time of Ambrose Pare whose (�nures de Chirurgie were published in 1575. The twelfth chapter of that volume, as translated by Thomas Johnson in 1605, shows ‘ by what means arms, legs, and hands may be made by art, and placed instead of the natural arms, legs, and hands that are cut off or lost.

The accompanying figures are copies of his drawing of ‘ an I made artificially of iron (fig. 1),’ and of ‘ the form of an arm made of iron verie artificially (fig. 2).’ He also gives a drawing of ‘a wooden leg made for a poor man’ (fig. 3), which is simply the common wooden leg with bucket receptacle still in use. No improvements worthy of record were made from the time of Abrose Pare to the beginning of the present century, when Baillif of Berlin constructed a hand which did not exceed a pound in weight, and in which the fingers, without the aid of the natural hand, not only exercised the movements of flexion and extension, but could be closed upon and retain light objects, such as a hat and even a pen. ‘Artificial hands,’ says Mr. Heather Bigg, ‘ are now constructed, by means of which a pin may be picked up from the ground, a glass raised to the lips, food carried to the mouth, and a sword drawn from its scabbard, and held with considerable firmness; while a combined arm and hand is fabricated, which is equal to the ordinary requirements of histrionic declamation.’�Orthopraxy, 1865, p. 157. The utility of an artificial arm depends much on the nature of the stump. A stump above the elbow is best suited for an arm when it gradually tapers to its lowest end, and terminates in a rounded surface. When an arm is removed at the shoulder-joint, and there is no stump, an artificial arm can still be fixed in its proper place by means of a corset. In amputation below the elbow joint, the best stump is one which includes about two-thirds of the fore-arm; while a stump formed by amputation at the wrist is very unsatisfactory. The simplest form of artificial arm intended to be attached to a stump terminating above the elbow, ‘ consists of a leathern sheath accurately fitted to the upper part of the stump. The lower end of the sheath is furnished with a wooden block and metal screw-plate, to which can be attached a fork for holding meat, a knife for cutting food, or a hook for carrying a weight.’�Op. cit. .p. 160. The arm should he so carried as to represent the position of the natural arm when at rest. It is retained in its position by shoulder and breast straps, and forms a light, useful, and inexpensive substitute for the lost member. More complicated, and therefore more expensive pieces of apparatus are made, in which motion is given to the fingers, a lateral action of the thumb is obtained, and the wrist-movements are partially imitated; and a degree of natural softness is given to the hand by a covering of gutta-percha and India-rubber. Such a hand, says Mr. Bigg, is often more symmetrical in aspect than the natural hand, but it possesses no efficient grasping power. Hence provision has to be made for attaching various instruments to its palm, such as special hooks, which can be removed at pleasure, for driving, shooting, &c.; apparatus for using the knife and the fork, for grasping the pen, &c.: indeed, the number and variety of instruments capable of being applied to an artificial hand are extremely great. Nothing has tended so much to the very highest development of artificial arms and hands, as an accident which happened more than a quarter of a century ago to the celebrated French tenor, M. Roger, who lost his right arm above the elbow.

It was necessary, for his future appearance on the stage, that he should have an artificial limb, which would serve the purposes of histrionic action, and permit him to grab a sword and draw it from its scabbard. Such a contrivance was invented in 1845 by Van Petersen, a Prussian mechanician, and the French Academy of Sciences commissioned MM. Gambey, Rayer, Valpeau, and Magendie to report upon it. For a history of the nature of the limb, the reader is referred to the report which appeared in the Comptes Rendus for that date, or to Mr. Bigg’s Orthopraxy, pp. 176�181. The apparatus, which weighs less than 18 ounces, was tested upon a soldier who had lost both arms. By its aid he was enabled to pick up a pen, take hold of a leaf of paper, &c.; and the old man’s joy during the experiment was so great, that the Academy presented him with a pair of these arms. Van Petersen’s conceptions have been extended and improved by Messr. Charriere, the celebrated surgical mechanics of Paris, aided by M. Huguier, the well-known surgeon. A very marvelous arm has also been almost simultaneously constructed by M. Bechard, which,’ by means of a single point of traction, placed in pronation, executes first the movement of supination, next in succession the extension of the fingers and abduction of the thumb: the hand is then wide open.’ -Bigg, op. cit. p. 190.

Artificial legs having fewer requirements to perform than artificial arms, are comparatively simple in structure. We borrow the description of our figure of the ordinary bucket leg in common use amongst the poorer classes from Mr. Bigg’s Orthopraxy. ‘ It consists of a hollow sheath or bucket, A. accurately conformed to the shape of the stump, and having�in lieu of the more symmetric proportions of the artificial leg�a ‘ pin,’ B, placed at its lower end to insure connection between it and the ground. This form of leg is strongly to be recommended when expense is an object, as it really fulfils all the conditions excepting external similitude embraced by a better piece of mechanism. It is likewise occasionally employed with benefit by those patients who, from lack of confidence, prefer learning the use of an artificial leg, by first practicing with the commonest substitute.’ As, when the body rests on a single leg, the center of gravity passes through the tuberosity of the ischium, it is essential that the bucket should be so made as to have its sole point of bearing against this part of the pelvis.

Of the more complicated forms of artificial leg three are especially popular. The first of these is of English origin, and owing to its having been adopted by the late Marquis of Anglesea, is known as the Anglesea leg. For a description of it, the reader is referred to Gray’s work on Artificial Limbs, one of the firm of Grays having been the constructor of the legs used by the marquis. This was for a long time the fashionable artificial leg. The second leg worthy of notice is that invented by an American named Palmer, and called the Palmer leg. From its lightness and the greater ease of walking with it, it has long superseded the Anglesea-leg in America. In the third of these legs, also invented in America, and known as Dr. Bly’s leg, the principal faults of the two other legs have been completely overcome. The advantages of this leg are thus summed up by Mr. Bigg, who has fully described and figured its mechanism: (1.) Adaptation to all amputations either above or below the knee. (2.) Rotation and lateral action of the ankle-joint. (3.) Power on the part of the patient to walk with ease on any surface, however irregular, as, owing to the motion of the ankle-joint, the sole of the foot readily accommodates itself to the unevenness of the ground, which is an advantage never before possessed by any artificial limb. (4.) The ankle-joint is rendered perfectly indestructible by ordinary wear, owing to its center being composed of a glass ball resting in a cup of vulcanite; thus it never gets out of repair, as the Anglesea leg but too frequently does, and the original cost is almost the only one the patient incurs. (5.) The action of the ankle-joint is created by five tendons, arranged in accordance with the position assigned to them in a natural leg. These tendons are capable of being rendered tight or loose in a few instants, so that the wearer of the leg has the power of adjusting with precision the exact degree of tension from which he finds the greatest comfort in walking, and also of giving the foot any position most pleasing to the eye. (6.) There is a self-acting spring in the knee-joint, urging the leg forward in walking, and imparting automatic motion, thus avoiding the least trouble to the patient, who finds the leg literally and not metaphorically walk by itself. (7.) The whole is covered by a beautiful flesh-colored enamel, thus avoiding the clumsy appearance of the wood, as is always found in an Anglesea leg, admitting of its being washed with soap and water like the human skin. (8). At the knee-joint there is a mechanical arrangement representing the crucial ligaments, and affording natural action to that articulation by which all shock to the stump in walking is avoided. This leg is patented, and as might be expected, is somewhat expensive.

In cases of arrested development of the lower limbs, short-legged persons may be made of the ordinary height by the use of two artificial feet placed twelve or more inches below the true feet, and attached to the legs by means of metallic rods, jointed at the knee and ankle.

Other parts not entitled to be called limbs, can also be replaced by mechanical art�such as the nose, lips, ears, palate, cheek, and eye. In the present advanced state of plastic surgery, deficiencies of the nose, lips, and palate can usually be remedied by an operation; cases, however, may occur where an artificial organ is required. Artificial ears are molded of silver, painted the natural color, and fixed in their place by a spring over the vertex of the head. Loss of an eye causes sad disfigurement; but the artificial eyes of Boissonneau (see his Renseigements G�n�raux sur les Yeux Artiftciels, leur Adoption et leur Usage), which have been shown in all the recent public exhibitions, completely throw all others in the shade, and cannot be detected without the closest inspection. For further details on all these subjects we must refer to Mr. Bigg’s volume, which is a complete encyclop�dia on these and allied topics.

July 12, 2006

FILTER, FILTRATION

Filed under: engineering, illustrations — Erik @ 6:48 pm

FILTER, FILTRATION. When solid matter is suspended in a liquid in which it is insoluble, it may be separated by various means. Under the article FlNlNG, various methods of causing such suspended matter to collect together and sink to the bottom or float on the surface, and thereby clearing the liquid, are described. The process of filtration consists in passing the liquid through some porous substance, the interstices of which are too small to admit of the passage of the solid particles, the principle of the action being the same as that of a sieve; but as the particles of fluids are immeasurably small, the pores must be extremely minute.

One of the simplest forms of filter is that commonly used in chemical laboratories for separating precipitates, &c. A square or circular piece of blotting-paper is folded in four, the corner where the four folds meet is placed downwards in a funnel, and one side is partly opened, so that the paper forms a lining to the funnel. The liquid passes through the pores of the paper, and the solid matter rests upon it. The chief advantages of this filter are its simplicity, and the ease with which the solid matter be removed and examined.

A simple water-filter for domestic purposes is sometimes made by stuffing a piece of sponge in the bottom of a funnel or the hole of a flower-pot, and then placing above this a layer of pebbles, then a layer of coarse sand, and above this a layer of pounded charcoal three or four inches in depth. Another layer of pebbles should be placed above the charcoal, to prevent it from being stirred up when the water is poured in. It is obvious that such a filter will require occasional cleaning, as the suspended impurities are left behind on the charcoal, &c. This is best done by renewing the charcoal, &c., and taking out the sponge and washing it. By a small addition to this, a cottage-filter may be made, which, for practical use, is quite equal to the most expensive filters of corresponding size. It consists of two flower-pots, one above the other; the lower one is fitted with the sponge and filtering layers above described, and the upper one with a sponge only. The upper pot should be the largest, and if the lower one is strong, the upper one may stand in it, or a piece of wood with a hole to receive the upper pot may rest upon the rim of the lower one. The two pots thus arranged are placed upon a three-legged stool with a hole in it, through which the projecting part of the lower sponge passes, and the water drops into a jug placed below. The upper pot serves as a reservoir, and its sponge stops the coarser impurities, and thus the filtering layers of the lower one may be used for two or three years without being renewed, if the upper sponge be occasionally cleaned. Care must be taken to wedge the upper sponge tightly enough, to prevent the water passing from the upper pot more rapidly than it can filter through the lower one.

A great variety of filters are made on a similar principle to the above, but constructed of ornamental earthenware or porcelain vessels of suitable shape. It would occupy too much space to enter upon the merits of the filters of different makers, especially as there is really very little difference between them in point of efficiency, and nearly all the domestic filters that are offered for sale are well adapted for their required purpose. In purchasing a filter, the buyer must not be satisfied with merely seeing that the water which has passed through it is rendered perfectly transparent�this is so easily done by a new and clean filter�but he should see that the filter is so constructed as to admit of being readily cleansed, for the residual matter must lodge somewhere, and must be somehow removed.

When large quantities of water have to be filtered, this becomes a serious difficulty, and many ingenious modes of overcoming it have been devised. In most of these, water is made to ascend through the filtering medium, in order that the impurities collected on it may fall back into the impure water. Leloge’s ascending filter consists of four compartments, one above the other; the upper part, containing the impure water, is equal in capacity to the other three. This communicates by a tube with the lower one, which is of small height. The top of this is formed by a piece of porous filtering-stone, through which alone the water can pass into the third compartment, which is filled with charcoal, and covered with another plate of porous stone. The fourth compartment immediately above the third, receives the filtered water, which has been forced through the lower stone, the charcoal, and the upper stone. A tap is affixed to this, to draw off the filtered water, and a plug to the second or lower compartment, to remove the sediment.

In the diagram-showing this filter in section, the figures 1, 2, 3, and 4 indicate the corresponding compartments. At f, the top of the tube by which the first and second compartments communicate, a sponge may be placed to stop some of the grosser impurities.

Since 1831, when this filter was contrived, a number of ascending filters have been patented, many of them being merely trifling mollifications of this. Bird’s Siphon Filter is a cylindrical pewter vessel containing the filtering media, and to it is attached a long toil of flexible pewter pipe. When used, the cylinder is immersed in the water-butt or cistern; and the pipe uncoiled and bent over the edge of the cistern, and brought down considerably below the level of the water. It is then started by applying the mouth to the lower end, and sucking it till the water begins to flow, after which it continues to do so, and keeps up a large supply of clear water. This, of course, is an ascending filter, and the upward pressure is proportionate to the difference between the height of the water in the cistern and that of the lower end of the exit tube. See SIPHON. Sterling’s filtering tanks are slate cisterns divided into compartments, the water entering the first, then passing through a coarse filter to a second, and from there through a finer filter to the main receptacle, where the filtered water is stored and drawn off for use.

A common water-butt or cistern may be made to filter the water it receives by the following means : Divide the cistern or butt into two compartments, an upper and a lower, by means of a water-tight partition or false bottom; then take a wooden box or small barrel, and perforate it closely with holes; fit a tube into it, reaching to about the middle of the inside, and projecting outside a little distance; fill the box or barrel with powdered charcoal, tightly rammed, and cover it with a bag of felt: then fit the projecting part of the tube into the middle of the false bottom.

It is evident that the water can only pass from the upper to the lower compartment by going through the felt, the charcoal, and the tube, and thus, if the upper part receives the supply, and the water for use is drawn from the lower part, the whole will be filtered. It is easily cleaned by removing the felt and washing it.

Various means of compressing carbon, into solid porous masses have been patented, and filters are made in which the water passes through blocks of this compressed carbon. Most of these are well adapted for the purpose, but their asserted superiority over filters composed of layers of sand and charcoal is doubtful. A very elegant and convenient portable filter for soldiers, travelers, and others who may require to drink from turbid ponds and rivers, was constructed of Ransom’s filtering stone, and is also made of

the compressed carbon. A small cylinder of the stone or carbon is connected with a flexible India-rubber tube in such a manner that the cylinder may be immersed in a river, the mouth applied to a mouth-piece at the other end of the tube, and the water drawn through the filtering cylinder.

The filtration of water on a large scale will be treated of under WATER-SUPPLY.

Some very interesting experiments were made by Mr. H. M. Witt, to ascertain whether soluble matter, such as common salt, is in any degree removed from water by filtration. Theoretically, it has been assumed that this is impossible, since the filter only acts mechanically in stopping suspended particles; but the results of Mr. Witt’s experiments show that from five to fifteen per cent, of the soluble salts were separated by sand-filters such as above described. This is a curious and interesting subject, well worthy of further investigation. Another most important matter, on which a series of accurate experiments is required, is to ascertain to what extent soluble organic matter may be decomposed by filtration, especially by charcoal filters, and to ascertain how long charcoal and other porous matter retains its property of acting on organic, matter in watery solution. The power of dry charcoal in decomposing organic matter in a gaseous state is well established (see below), and it is also well known that fresh charcoal acts powerfully upon organic matter in solutions, but the extent to which this power is retained in the charcoal of a filter in continuous action has not been satisfactorily ascertained. This is of the highest importance, as it sometimes happens that water of brilliant transparency, and most pleasant to drink, on account of the carbonic acid it contains, is charged with such an amount of poisonous organic matter as to render its use as a daily beverage very dangerous. Charcoal obtained from burning bones is still more efficacious than charcoal from wood. A filter of animal charcoal will render London porter colorless. Loam and clay have similar properties. Professor Way found that putrid mine and sewer-water, when passed through clay, dropped from the filter colorless and inoffensive.

When a liquid contains mucilaginous or other matter having viscous properties, there is considerable difficulty in filtering it. as the pores of the medium become filled up and made water-tight. Special filters are therefore required for syrups, oils, &c. Such liquids as ale, beer, &c., would be exceedingly difficult to filter, and therefore they are clarified by the processes described under fining. Oil is usually passed through long bags made of twilled cotton cloth (Canton flannel). These are commonly 4 to 8 feet long, and 12 to 15 inches in diameter, and are enclosed in coarse canvas bags, 8 or 10 inches in diameter, and thus the inner filtering-bag is corrugated or creased, and a large surface in proportion to its size is thus presented. Syrups are filtered on a small scale by confectioners, &c., by passing them through conical flannel bags, and on a large scale in the creased tag -filter just described. Thick syrups have to be diluted or clarified with white of egg, to collect the sediment into masses, and then they may be filtered through a coarse cloth strainer. Vegetable juices generally require to be treated in this manner.

The simple laboratory filter has to be modified when strong acid or alkaline solutions, or substances which are decomposed by organic matter, require filtration. Pure silicious sand, a plug of asbestos, pounded glass, or clean charcoal, are used for this purpose. B�ttger recommends gun-cotton as a filter for such purposes. He has used it for concentrated nitric acid, fuming sulphuric acid, chromic acid, permanganate of potash, and concentrated solutions of potash and aqua regia. He says that properly prepared gun-cotton is only attacked at ordinary temperatures by acetic ether.

Filtering paper for laboratory purposes requires to be freed from inorganic impurities that are soluble in acids, &c.; this is effected by washing the paper with hydrochloric acid, or, when thick, with nitric and hydrochloric acid, and removing the acid by washing thoroughly with distilled water.

When a considerable quantity of liquid has to pass through a filter, it is sometimes desirable that it should be made to feed itself. In the laboratory, this is done by inverting a flask filled with the liquid over the filtering funnel, the mouth of the flask just touching the surface of the liquid when at the desired height in the funnel. As soon as it sinks below this, air enters the flask, and some liquid falls into the funnel. On a large scale, self-acting filters are fed by the common contrivance of a ball-cock and supply-pipe.

Air-Filters�The extraordinary powers of charcoal in disinfecting the gaseous products evolved from decomposing animal and vegetable matter, have been made available by Dr. Stenhouse in constructing an apparatus for purifying air that is made to pass through it. A suitable cage, containing charcoal in small fragments, is fitted to the opening from which the deleterious gases issue, and is found to render them perfectly inodorous, and probably innocuous. The first application of this was made in 1854, when a charcoal air-filter was fitted up in the justice-room of the Mansion House, London, the window of which opens above a large urinal, the smell of which was very offensive in the room.

The filter at once destroyed the nuisance, and the charcoal has Keen found to last many years without the need of renewal. 103 of such filters have been applied to the outlets of the sewers of one district of the city of London, and no bad smell is observable where they are placed, and no obstruction offered to the ventilation of the sewers. They have been applied with like results in two or three county towns. The subject is fully treated by Dr. Stenhouse in a letter to the lord mayor, published by Churchill (London). Charcoal respirators are small air-filters of the same kind applied to the mouth. See RESPIRATOR.

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