Cooley's Cyclopaedia of Practical Receipts Volume I Part 259

=GEL'ATIN.= _Syn._ GELATINE; GeLATINE, Fr.; GELATINA, L. Animal jelly, obtained by the prolonged action of boiling water on the organic tissue of the bones, tendons, and ligaments, the cellular tissue, the skin, and the serous membranes. Glue and size are coa.r.s.e varieties of gelatin, prepared from hoofs, hides, skins, &c.; and isingla.s.s is a purer kind, obtained from the air bladders of some other membranes of fish.

_Prop., &c._ Gelatin is insoluble in cold water, but dissolves with greater or less readiness on the application of heat, according to the source where it is obtained, and in this state forms a tremulous and transparent jelly on cooling; it is insoluble in both alcohol and ether, and is decomposed by the strong alkalies and acids; with tannic acid it forms an insoluble compound of a buff colour, which is the basis of leather; when acted on by cold concentrated sulphuric acid, it yields glycocoll or gelatin sugar; and when boiled with strong alkalies, it yields glycocoll and leucine. Chlorine pa.s.sed into a solution of gelatin occasions a dense white precipitate (chlorite of gelatin), which ultimately forms a tough, elastic, pearly ma.s.s, somewhat resembling fibrin.

_Tests._ Its aqueous solution is recognised as follows:--1. It gelatinises on cooling. 2. It is precipitated by alcohol. 3. Bichloride of mercury gives a whitish flocculent precipitate. 4. Tannic acid or infusion of galls gives a copious yellowish-white, curdy precipitate, which, on being stirred, coheres into an elastic ma.s.s, insoluble in water, and incapable of putrefaction, and which, when dried, a.s.sumes the appearance of over-tanned leather. 5. The gelatinising property is destroyed by nitric acid. 6. It is not affected by either alum or acetate of lead. In this respect it differs from chondrin.

_Qual._ The goodness of commercial gelatin intended for food is readily proved by pouring boiling water over it, and digesting the two together for a short time. If it is pure and wholesome, its colour remains unaltered, and during its solution it continues entirely free from smell.

The resulting solution and jelly are also odourless, neutral to test-paper, free from unpleasant taste, and perfectly transparent. If it forms a yellow gluey-looking ma.s.s, and evolves an offensive odour, it should be rejected as of inferior quality, and unfit for culinary purposes.

_Uses, &c._ Gelatin is largely employed as an article of food, as in soups, jellies, &c.; but its value in this respect has been, perhaps, overrated.[329] Animals fed exclusively on gelatin die of starvation. But when mixed with other food, especially with substances abounding in alb.u.men, casein, or fibrin, gelatin may be useful as an aliment, and serve directly to nourish the gelatinous tissues. (Liebig.) Hence gelatin is a fitting substance to form part (but only a part) of the diet of convalescents, as it conveys nutrition directly to these tissues, without tasking the diminished powers of life for its conversion; but its use should be accompanied by a proper quant.i.ty of azotised animal food to supply the elements to the blood, for the support and increase of the muscular tissue, or fleshy portion of the body. In France gelatin obtained from bones is employed as a part of the diet in hospitals with the best effect, materially abridging the period of convalescence; but when given alone, all animals soon become disgusted with it, and die if not supplied with other food. (D'Arcet.) See GLUE, ISINGLa.s.s, and _below_.

[Footnote 329: The reader interested in this subject should consult a paper by Carl Voit in the 'Zeitschrift fur Biologie,' viii, 297-388.]

=Gelatin, Bone.= Obtained from crushed bones by boiling with water, or by the action of steam and water successively, either with or without pressure; or by maceration in dilute hydrochloric acid, to extract the phosphate of lime, the remaining gelatinous ma.s.s being well washed in cold water, and afterwards dissolved in boiling water in the usual manner. A little carbonate of soda is commonly added to the last water. Gelatin has even been extracted from fossil bones. "A soup was prepared from one of the bones of the great mastodon by the prefet of one of the departments of France." (Pereira.) Butchers' meat contains, on an average, 24% of dry flesh, 56% of water, and 20% of bone. The last will yield, by proper treatment, nearly 1-3rd of its weight of dry gelatin, or a quant.i.ty equal to about 6% of the meat from which it is cut. This, as well as other varieties of gelatin, is frequently blanched by sulphurous acid or animal charcoal, and tinged of various colours with the ordinary vegetable dyes.

Thus, blue is given with sulphate of indigo or the juice of blue berries; green, with the juice of spinach; and red, with juice of red-beet.

=Gelatin, French.= _Syn._ CAKE GELATIN. Gelatin made up into small thin cakes, like the finer sorts of glue. A good deal of it is prepared in Paris from the cuttings of the skins used in making kid gloves and slippers.

=Gelatin, Patent.= Various qualities of gelatin are manufactured from glue pieces, or cuttings of the hides of beasts and skins of calves, and from inferior isingla.s.s. According to Mr Nelson's specification, the crude materials, freed from hair, wool, flesh, and fat, after being thoroughly washed and 'scored,' are macerated for 10 days in a lye of caustic soda, and are then placed in covered vessels at a temperature varying from 60 to 70 Fahr., until they become tender; they are next washed to free them from alkali, and are then exposed to the vapour of burning sulphur until they acquire a sensibly acid reaction; they are now dissolved in water contained in earthen vessels heated to 150 Fahr., and the solution, after being strained, is put into 'settling vessels,' and heated to 100 to 120 Fahr., for 8 or 9 hours; at the end of this time the clear liquor is drawn off, and poured on the 'cooling slabs,' to the depth of about 1/2 an inch.

As soon as the jelly is cold, it is cut into pieces, and washed in water until perfectly free from acid. It is then redissolved in water at about 85, the solution poured out on slabs as before, and when cold, it is cut up, and, lastly, dried on nets.

According to another specification (Rattray's Patent) glue-pieces are steeped in water until they begin to putrefy, then washed with water, drained, and put from 12 to 24 hours into water strongly soured with sulphurous acid; they are afterwards washed first with cold water, and then in water at 120 Fahr., and are lastly converted into size by digestion for 24 hours in water at 120 Fahr., the resulting solution being filtered through bags of double woollen-cloth.

Patent gelatins are often sold cut up in imitation of 'picked isingla.s.s,'

to which, for the preparation of jellies, soups, and blancmanges, they are not much inferior.

=Gelatin, Rough.= _Syn._ GELATINE BRUT, Fr. From the skulls of oxen, the spongy insides of the horns and ribs, and from several other soft bony parts (deprived of fat), by washing them in water, digesting in an equal weight of hydrochloric acid of 6 Baume, in cold weather, and 4 or 5 in summer, for 10 days, then in acid of only 1 Baume for 24 hours longer; afterwards soaking and washing in successive portions of cold water until all the acid is washed out, adding an ounce of carbonate of soda to the last water. Used to make glue, &c. A similar article is prepared from the bones of sheep. The pieces, after being treated as above, are steeped in boiling water for a few minutes, wiped dry, and shaken together in a bag to remove the internal pellicle; after which they are cut into squares or dice to disguise them, and finally dipped into a hot solution of gelatin to varnish them. In this state the article is called 'GELATINE BRUT FIN,'

Used to make soup. It keeps better than the cakes of portable soup. When less carefully prepared, it is also used to make glue for fine work. See BONE GELATIN.

=GELEE (pour le Goitre).= See LINIMENT OF IODIDE OF POTa.s.sIUM.

=GELSEMIUM SEMPERVIRENS.= _Syn._ GELSEMIUM NITRIDUM, GELSEMIUM SEMPERVIRENS, GELSEMIUM LUCIDUM, ANONYMUS SEMPERVIRENS, BIGNONIA SEMPERVIRENS; LISANTHUS SEMPERVIRENS. The YELLOW JASMINE, or WOODBINE. The CAROLINA JASMINE.

Different botanists have placed the plant in different natural orders. De Candolle a.s.signs it to the _Loganiaceae_; Decaisne to the _Apocynaceae_; Chapman to the _Rubiaceae_.

The root, which is the only part of this plant employed in medicine, and of which a fluid extract has been introduced into the United States Pharmacopia, as met with in English commerce occurs in two states; either in packets prepared by the shakers of New Lebanon, which contain the root in small pieces, formed into a compact ma.s.s by hydraulic pressure, and in which state it is difficult to powder; or it is simply sold cut up into pieces varying from two to eight inches in length, and one-third to three fourths of an inch in diameter. It is frequently mixed with about half its bulk of long, wiry, pale-brown rootlets.

The so-called gelsemium root consists chiefly of subterranean stem with a small proportion of true root, occasionally a slender piece of the aerial stem may be found intermixed, and is readily distinguished by its purplish colour and hollow centre, and by the silky and tow-like fibre, rendered visible when the epidermis is peeled off (fig. 1 _e_).

The true root is hard and woody, slightly undulated in outline, very sparingly branched, except in the slender pieces, externally of a pale brown colour, nearly smooth, and furnished with a thin scurfy cuticle, which is slightly cracked longitudinally. When a transverse section is examined with a lens, the bark of the root is seen to be very thin, and to consist of two layers, the inner one being usually almost as pale as the woody portion, and of somewhat soft texture, the outer one is darker and more compact (fig. 1 _b_, _c_).

The meditullium, or woody portion of the root occupies nearly its whole diameter, is of a pale yellowish bright colour, the yellow tint becoming much more distinct when the root is wetted. The medullary rays are white and very distinct, and the woody tissue between the rays is very porous, the pores being very small, but visible to the unaided eye, especially when the root is broken instead of cut (fig. 1 _d_). There is no pith or central cavity in the root. The root has a bitter taste and pleasant flavour, somewhat between those of senega and green tea; this is more readily perceived in the tincture.

The subterranean stem (fig. 1 _a_) is also furnished with rootlets, but is easily distinguished from the root by the presence of a small, dark coloured, central cavity representing the pith, and by the external surface being rougher, and frequently variegated with dark longitudinal lines, which are the remains of the same purplish cuticle which presents so marked a feature in the aerial stem. The bark is thicker than that of the true root, and the inner layer is usually dark brown. If the subterranean stem is broken slowly and carefully, a thin row of silky fibres projects fully a quarter of an inch from the broken edge. The fibres do not appear when the bark of the root is broken, and thus serve to distinguish the stem of this drug from the root. Experiments as to the relative value of the bark of the root and stem are wanting. The bark of the stem has the same bitter taste as that of the root, and if it be hereafter shown that it is equally active, the above character of scattered strong fibres, taken in conjunction with the flavour of the drug and its porous structure, will serve to distinguish it from all other roots and stems used in materia medica.[330]

[Footnote 330: Holmes.]

_Medicinal properties._--The American medical journals record the successful administration of gelsemium in a great number and variety of diseases, including intermittent, remittent, typhoid, and yellow fevers, the irritative fevers of childhood, inflammation of the lungs and pleura, dysentery, rheumatism, and other inflammatory affections, neuralgia, obstinate menstruation, delirium tremens, morbid wakefulness, St. Vitus'

dance, hysteria, epilepsy, spasmodic stricture of the urethra, and gonorrha. Dr Hurd, an American physician, reports very favorably of the drug as a cardiac sedative, and considers it more efficient than any other remedy in the palpitation and the difficult breathing that accompany heart disease; and Dr Hill, of Maine, finds it when combined with bromide of pota.s.sium useful in irritable bladder.

[Ill.u.s.tration]

Its princ.i.p.al use, however, in American medical practice has been as a febrifuge. In periodic fevers it has been employed with great advantage, as well as in cases of intermittent fever, which having failed to yield to quinine alone, succ.u.mbed, when this latter medicine was combined with gelsemium.

In England gelsemium has been successfully employed for the relief of facial neuralgia, or of the pain caused in the face and jaws by decayed teeth; as well as in obscure nervous affections and severe headaches. It is given princ.i.p.ally in the form of tincture; but sometimes in powder in doses of from one to two grains.

The therapeutic action of gelsemium is believed to be due to the sedative effect it exercises on the nervous and arterial systems--hence its power in controlling the nervous irritability so prevalent during fever. In moderate doses it causes a sensation of agreeable langour, accompanied with muscular relaxation; in larger doses, dizziness, dilated pupil, double vision, general muscular debility and prostration; these symptoms being accompanied by a diminution in the force and frequency of the pulse as well as in the respiration. At the same time the patient becomes insensible to pain; but is free from stupor and delirium. These symptoms are said to pa.s.s off, after a time, and to be attended with no unpleasant results.

The 'Lancet' as well as many of the American medical journals record several cases of poisoning arising from giving an overdose of this drug.

The symptoms are a great prostration of nervous energy, accompanied by paralysis of sensation and motion. When death occurs it is probably owing to syncope. The antidotes are, first, an emetic, and after this has acted, stimulants, such as carbonate of ammonia with brandy, or aromatic spirits of ammonia. In cases accompanied with insensibility, recourse should be had to electricity.

Kollock, in the 'American Journal of Pharmacy' for 1855, states that he found the root on a.n.a.lysis to yield volatile oil, dry acrid resin, fatty resin, fixed oil, gallic acid, starch, pectic acid, alb.u.men, extractive matter, lignin, gum, a yellow colouring matter, mineral matter (chiefly salts of pota.s.sium, calcium, magnesium, iron and silica), and an alkaloid, to which the name gelseminine or gelsemia has been given. Kollock also states that the leaves and flowers contain the same ingredients as the root, although in much smaller quant.i.ties.

Eberle, in the 'American Journal of Pharmacy' for 1864, says he failed to obtain gelseminine from the root. In a paper contributed to the 'American Journal of Pharmacy,' for January, 1870, by Dr Wormley, the author stated that he said he not only succeeded in obtaining pure gelseminine from the root, but also a peculiar acid which he calls gelseminic, or gelsemic[331]

acid; which he regards as existing in combination with the gelsemia, forming the gelsemate of gelsemia.

[Footnote 331: Professor Sonneschien, having submitted the so-called _Gelseminic Acid_ to a.n.a.lysis thinks there can be no doubt that it is perfectly identical with aesculin, a glucoside obtained from the bark of the horse-chesnut--the _Esculus hippocastanum_.]

Probably the alkaloid gelseminine may at some future time be introduced into medicine, since it would appear to be the chief ingredient to which the root owes its activity. It is strongly poisonous. Dr Wormley injected one eighth of a grain under the skin of a large cat, which in 40 minutes exhibited great prostration, and died in an hour and a half from the time of the injection of the poison. The properties of the gelseminic acid, the resin, the volatile oil, and other ingredients of the root, have not been fully investigated. See TINCTURE OF GELSEMIUM, GELSEMININE.

In the 'American Journal of Pharmacy' for April, 1877, Dr Wormley gives the following directions for the preparations of gelseminic acid, and gelsemine:--A given volume of fluid extract, acidulated with acetic acid, is slowly added with constant stirring to about eight volumes of water; after the separated resinous matter has completely deposited, the liquid is filtered, and the filtrate concentrated on a water bath, to something less than the volume of fluid extract employed. The gelseminic acid is then extracted from the concentrated fluid by ether, after which the liquid is treated with slight excess of carbonate of sodium, and the gelsemine extracted with ether or chloroform. For the extraction of the first of these principles, it is not essential that the liquid should be acidulated, but in the presence of a free acid the results are more satisfactory.

=GEMS=. _Syn_. JEWELS; GEMMae, L. "Gems are precious stones, which, by their colour, limpidity, l.u.s.tre, brilliant polish, purity, and rarity, are sought after as objects of dress and decoration. They form the princ.i.p.al part of the crown jewels of kings, not only from their beauty, but because they are supposed to comprise the greatest value in the smallest bulk; for a diamond, no larger than a nut, or an acorn, may be the representative sign of the territorial value of a whole country, the equivalent in commercial exchange for a hundred fortunes, acquired by severe toils and privations." "Among these beautiful minerals mankind have agreed in forming a select cla.s.s, to which the t.i.tle of gems or jewels has been appropriated; while the term precious stone is more particularly given to substances which often occur under a more considerable volume than fine stones ever do. Diamonds, sapphires, emeralds, rubies, topazes, hyacinths, and chrysoberyls, are reckoned the most valuable gems;--crystalline quartz, pellucid, opalescent, or of various hues, amethyst, lapis lazuli, malachite, jasper, agate, &c., are ranked in the much more numerous and inferior cla.s.s of ornamental stones." (Ure.)

_Tests._ The only tests applicable to gems and precious stones are the determination of their relative hardness and their specific gravity. By the first test, pastes or fact.i.tious gems are readily detected; but beyond this, owing to the difficulty of applying it, it ceases to be useful to persons unconnected with the trade. The determination of the specific gravity is, however, of more general application, as gems are generally dismounted when offered for sale, or are so set that they may be removed from their 'mountings' without injury or inconvenience. See SPECIFIC GRAVITY, and _below_.

_Obs._ The relative hardness of the different substances is measured by the power they possess of cutting or scratching the other substances having a smaller number attached to them in the table. Thus, no gem but the DIAMOND (20) will scratch either the RUBY (17) or the SAPPHIRE (16); and, for the same reason, a blue stone that will cut the EMERALD or the TOPAZ can be no other than the SAPPHIRE. The sp. gr. is ascertained in the usual manner, and will be found sufficiently indicative of the true nature of the stone when considered in connection with its other characteristics.

The index of refraction is a certain key to the quality of the stone, in the hands of those who are capable of determining it, and may be applied to either mounted or unmounted gems. The most convenient instrument for the purpose is Wollaston's 'REFLECTING-GONIOMETER,'

=Gems, Facti"tious.= These, with few exceptions, are made of very pure, fusible, highly transparent, and dense gla.s.s, usually termed 'PASTE' or 'STRa.s.s,' which is generally formed of oxide of lead, pota.s.sa, and silica, with small quant.i.ties of other ingredients to increase the brilliancy and clearness. The characteristic tints are imparted by the addition of metallic oxides. The beauty of artificial stones and gems depends, chiefly, upon the tint of the real stones being exactly imitated, and upon proper care and skill being exercised in the cutting, polishing, and mounting them. All the coloured gla.s.ses, and enamels, may be worked up into artificial gems.

TABLE _of the Hardness, Specific Gravity, and Refractive Power of the princ.i.p.al_ GEMS _and_ PRECIOUS STONES, _and some other_ MINERALS; _compiled expressly for this work_.

---------------------------------------------------------------------------------- Name. Relative Specific Gravity. Index of Reflection. Hardness. --------------------------------------------------------------------------------- Agate 12 26 Amethyst (occidental) 11 27 Calcareous spar 6 27 Chalk 3 27 Chrysolite 10 37 Cornelian 11 27 Crystal 11 26 Diamond (bluish) 19 33 } " (cubic) 18 32 } " (from Ormus) 20 37 } 2439 " (pink) 19 34 } " (yellowish) 19 33 } " (average colourless) 19 to 20 33 to 355 } Emerald 12 28 Fluor spar 7 35 1434 Garnet 12 44 1815 Gla.s.s { } 23 to 362 1525 to 2028 " (crystal or flint) {various} 30 " 36 1830 " 2028 " (plate) { } 25 " 26 1514 " 1542 Gypsum 5 23 Jasper (green) 11 27 " (reddish yellow) 9 26 Onyx 12 26 Opal 10 26 Quartz 10 27 1548 Ruby 17 42 } 1779 " (pale, from Brazil) 17 35 } " (spinelle) 13 34 1764 Sapphire (deep blue) 16 38 } 1794 " (paler) 17 38 } Sardonyx 12 26 Sch.o.e.rl 10 36 Topaz 15 42 " (Bohemian) 11 28 " (whitish) 14 35 Tourmaline 10 30 Zeolite 8 21 Zircon -- -- 1961 ----------------------------------------------------------------------------------

MM. Fremy and Feil have lately succeeded in manufacturing artificial corundum, ruby and topaz, having a composition the same as the natural stones. The process by which they have effected this consists in fusing together at a red heat, in the furnace of a gla.s.s works for a considerable time, a fusible aluminate (such as aluminate of lead), and some silicious body.

The silica is found to unite with the lead, and to liberate the alumina in the crystalline form. When equal weights of alumina and red lead are heated together in a crucible made of some refractory silicious substance, the above conditions if the temperature has been maintained sufficiently long and high ensue, and there is found in the crucible at the end of the operation a layer of silicate of lead, and very frequently another of pure crystallised alumina or corundum.

The ruby colour is given by adding to the mixture in the crucible two or three per-cent. of bichromate of potash, the blue being produced by the addition of a small quant.i.ty of oxide of cobalt, with a trace only of bichromate of potash. A film of silicate of lead very frequently adheres to the ruby crystals, and this has to be removed.

In some instances, however, the crystals occur nearly pure, and are precisely similar to the natural gems in crystalline form, composition, hardness, and l.u.s.tre.

Upon being heated, the artificial ruby, like the natural one, loses its rose colour, and recovers it again on cooling. It is said that the fact.i.tious gems. .h.i.therto obtained are not, as a rule, equal in l.u.s.tre to the natural ones, and are consequently not so well suited for jewellers'

work; also that they do not present to the lapidary conditions favorable to cleavage or cutting. They are, however, very well adapted for the works of watches. See ENAMELS, PASTES, &c.

=GENE'VA.= See GIN and HOLLANDS.

=GEN'TIAN ROOT.= _Syn._ GENTINae RADIX, L. The dried root of _Gentiana lutea_, or 'yellow gentian.' _Dose_, 10 to 30 gr.; as a simple bitter tonic, and stomachic, in dyspepsia, loss of appet.i.te, gout, &c. It was formerly a favourite remedy in agues. "Joined with galls or tormentil, and given in sufficient quant.i.ty, it has not failed in any intermittents in which I have tried it." (Dr Cullen.) In excessive doses it is apt to relax the bowels and disturb the system. When taken for some time, it imparts its bitter flavour to the perspiration and urine. See DECOCTION, EXTRACT, &c.