Part 180
5. (Ph. D., B. P.) The Dublin contains two formulæ for gallic acid, the one being based on that of Dumas or Scheele, the other on that of Graham or Liebig.--_a._ From galls (in coarse powder), 1 lb.; water, q. s. to make a stiff paste; a porcelain dish is ordered, and the exposure in the moistened condition is to be continued for 6 weeks; the solution of the first crop of crystals is to be made in 10 fl. oz. of boiling water, and when the filtrate has cooled to 80° Fahr., it is to be poured off from the crystals which have formed, which are then to be washed with ice-cold water, 3 fl. oz., and dried--first in blotting paper, and finally by a steam or water heat. By boiling the undissolved portion of the galls with 45 fl. oz. of fresh water, more crystals may be obtained.
_b._ Powdered gall-nuts, 1 lb., are steeped for 24 hours in water, 1 pint, and after being placed in a porcelain displacement apparatus, are treated with water, 1-1/2 pint, added in successive portions; oil of vitriol, 5 fl. oz., diluted with an equal volume of water, and allowed to cool, is now added to the percolated infusion, and after thorough admixture the liquid is filtered from the viscid precipitate which forms; oil of vitriol, 5 fl. oz. (diluted as before), is then added to the filtrate, the precipitates, enveloped in calico, are submitted to powerful pressure, and subsequently dissolved in oil of vitriol, 16 fl. oz., previously diluted with water, 56 fl. oz.; the solution is boiled for 20 minutes, and set aside for a week; at the end of this time the deposit which forms is dissolved in three times its weight of boiling water, and the solution treated as before.
_Prop._ Gallic acid forms small, feathery, and nearly colourless crystals, which have a beautiful silky lustre; that of commerce is usually of a pale-yellow colour; it is soluble in 100 parts of cold water, and in 3 parts of boiling water; it is also soluble in alcohol, and slightly so in ether; the aqueous solution is decomposed by exposure to the air; dissolved in hot oil of vitriol, it forms a deep, rich, red solution, which, when thrown into water, drops the gallic acid, deprived of some of its water. This substance is soluble in the alkalies, and dyes cloth like madder. When strongly heated, gallic acid is converted into metagallic acid, or into pyrogallic acid, according to the manner in which the heat is applied.
_Tests._ Gallic acid is distinguished from tannic acid by not affecting solutions of gelatin, the protosalts of iron, or the salts of the alkaloids, and by giving a deep bluish-black precipitate with the sesquisalts of iron, which disappears when the liquid is heated. It is distinguished from pyrogallic acid by its inferior insolubility in water, and by its not affecting the solutions of the protosalts of iron. To detect gallic acid mixed with tannic acid, the latter should be removed, either by digesting the substance in ether, or by immersing for some time in its solution a piece of skin depilated by lime, previously to applying the tests.
_Pur._ Free from colour; decomposed by heat; soluble in water and in rectified spirit. It turns preparations of the sesquioxide of iron, dissolved in water, of a bluish black colour, but throws down nothing from a solution of isinglass.
_Uses, &c._ The principal use of pure gallic acid is in the art of _photography_. It has recently been employed in _medicine_, as an internal astringent, in doses of 3 to 10 gr., thrice a day, or oftener; in hæmorrhage and fluxes, as well as for checking the night sweats in phthisis. Dr Todd says, that in all cases of internal hæmorrhage, or hæmorrhagic tendency, it is the best astringent or styptic we possess. As an external astringent, it is greatly inferior to tannic acid. It has been given in doses of 15 to 30 gr. in tape-worm, "but without any benefit." (Pereira.)
_Purification._ Gallic acid, as obtained by either of the above forms, is never quite pure; but it may be rendered absolutely pure by combining it with oxide of lead, and decomposing the compound (gallate of lead) by sulphuretted hydrogen. The sulphuret of lead acts like animal charcoal in removing the colour. (Liebig.) Commercial gallic acid "may be rendered nearly white by dissolving it in 20 times its weight of boiling distilled water, and causing the solution to traverse a stratum of prepared animal charcoal, spread upon a calico filter. When the liquid passes through colourless, it should be evaporated to 1-6th its volume, and then suffered to cool, in order to the separation of the crystallised acid." (Ph. D.)
=GALLIC FERMENTATION.= This name has been given to the peculiar process by which tannic acid is converted into gallic acid, under the joint influence of moisture and atmospheric oxygen. According to the researches of M. Antoine Larocque, the peculiar ferment of nut-galls which operates this change also converts sugar into alcohol and carbonic acid, in the same way as yeast does; whilst beer yeast, muscular flesh, and caseous matter change tannin into gallic acid. The similarity of the gallic and vinous fermentation may hence be reasonably inferred.
=GALLIUM.= A new metal discovered in August, 1875, by means of the spectroscope, by M. Lecoq Boisbaudran, in a specimen of blende from the mines of Pierrefitte, in the Pyrenees. The new element was named gallium in honour of France, the discoverer's native country.
Gallium gives a spectrum composed of two bands in the violet, one of the bands being brilliant, and of wave length 417, and the other, a feeble one of wave length, 403·3.
The Pierrefitte blende contains one part of gallium in four hundred thousand. It is, however, found much more abundantly in a black blende from Bensberg, on the Rhine, one hundred thousand parts of this latter yielding one part of gallium.
Gallium resembles lead in appearance, but is less blue in colour. Exposed to moist air it tarnishes slightly. It is a little harder than lead, is flexible, malleable, and may be easily cut with a knife. If melted and poured upon glass, it adheres to it, and forms a mirror which is whiter than that caused by mercury. A red heat fails to volatilise it to any appreciable extent, and it is only slightly oxidised at that temperature; therefore it is not tarnished when exposed to the air. Hot nitric acid dissolves it, but the cold acid has scarcely any action on it. It melts at 30·15 C. When once fused, it preserves the liquid condition even for several months at 0° C.,[324] until it is touched by some solid body, or by a piece of solid gallium, when it congeals to a crystalline solid, having a specific gravity of 5·93; when fused it has a specific gravity of 6·08. It crystallises in square octohedra. In properties gallium is more or less intermediate between the metals aluminium and indium.
[Footnote 324: In consequence of this curious property gallium was first described as a liquid metal.]
Chemical reactions of gallium:--The following are the chief reactions of the salts of gallium when in solution. With ammonia they give a white gelatinous precipitate, soluble, but not readily in excess of the precipitant; potash gives a similar precipitate, soluble in excess; acetate of ammonia, on boiling in a solution free from excess of acid, precipitates a basic compound; barium carbonate readily precipitates gallium salts in the cold. A sulphate and a chloride of gallium have already been obtained. These salts are both very soluble; the sulphate is a non-deliquescent substance, the chloride, on the contrary, is excessively so, and decomposed by a large excess of water. Gallium also forms an alum consisting of the double sulphate with ammonium. Gallium alum is a beautifully crystalline body, more soluble in cold than in hot water.
At a meeting of the 'Academie des Sciences' in March, 1878, M. de Baubradon stated that he had determined the atomic weight of gallium. The mean of two experiments showed it to be 69·9.
The 'Comptes Rendus' for February, 1878 (No. 7), contains a communication from MM. Lecoq de Boisbaudran and E. Jungfleisch, on the extraction of gallium from the ores in which it is found associated with indium.
The following is the process given by the authors:--The blende of Bendsberg is pulverised and then roasted in a Perret furnace, by which treatment the greater part of the indium is volatilised. The residue is treated with sulphuric acid in quantity sufficient to dissolve almost all the zinc, and there is thus obtained a residue which is treated with excess of sulphuric acid.
The persalts of iron present are then reduced by means of metallic zinc, and the filtrate fractionally precipitated with carbonate of sodium; the precipitates are redissolved in sulphuric acid, and the reduction with zinc and the fractional precipitation repeated, the latter operation being in both cases watched by the spectroscope.
The precipitate containing the gallium concentrated in a small bulk, is redissolved in acid, and the excess of the latter reagent removed by evaporation, after which it is boiled with much water. The filtrate separated from the sediment containing titanic acid, which form is treated with sulphuretted hydrogen, then mixed with acetate of ammonium and again treated with sulphuretted hydrogen, which throws down the galliferous sulphide of zinc free from alumina. Again the precipitate is dissolved in sulphuric acid, and the solution fractionally precipitated with carbonate of sodium, which operation, guided as it is by spectral examination, entirely removes the zinc. By once more dissolving in the exactly necessary amount of sulphuric acid, and treating with sulphuretted hydrogen, cadmium, lead, indium and zinc are removed, and the filtrate is then largely diluted with water and boiled. The bulky sub-salt of gallium which separates at this temperature is treated with potash, which leaves iron, indium, &c., undissolved, and the alkaline liquor when treated with sulphuretted hydrogen, and subsequently with sulphuric acid to slight acidity, yields a deposit consisting mainly of sulphide of indium.
The slightly acid liquid is then boiled with much water, and the deposit of sub-salt of gallium thus obtained is dissolved in potash, and the solution subjected to electrolysis, by which means a metallic deposit of gallium is obtained.
It is interesting to note how accurately many of the chemical physical properties to gallium had, previously to its discovery, been predicted by the Russian chemist, Mendelejeff, by reasoning on the so-called "periodic law," which he thus defines:--"The properties of the simple bodies, as also the properties and constitution of their combinations, are periodic functions of the atomic weights of the elements."
In 1864 an English chemist named Mr Newlands, observing certain relations existing between the atomic weights of many of the elements, was the first to arrange them in such a manner or serial form as to suggest that when certain gaps were observed in the atomic weights of a series, new elements might be assumed to exist. Guided by this theory, Mendelejeff affirmed that the "periodic law" not only indicates vacancies in the classificatory scheme of the known elements, but enables us to predict the properties of elements as yet undiscovered, and of their compounds. Thus, of one of the vacancies observable in the table of the elements arranged according to his classification, Mendeljeff asserted, that should the element (which he named _Eka aluminium_) with the corresponding atomic number be discovered, it would possess the following characteristics:--It would most probably, like indium and thallium, be discovered by the aid of spectrum analysis. Gallium, as we have seen, was found by this means. The formula of its oxide would be El_{2}O_{3}; the oxide of gallium is best represented by Ga_{2}O_{3}.
The salts would have the general formula ElX_{3}; the salts of gallium have most probably the general formula GaX_{3}. It will form an alum isomorphous with common alum, this we have seen gallium does. Its salts would be precipitable by barium carbonate; the gallium salts are thrown down by this reagent. It would not oxidise in the air; gallium does not tarnish upon exposure to the air. It would decompose water at a red heat; gallium readily does this at high temperatures. Its specific gravity (and this is very remarkable) would be about 5·9; gallium has a specific gravity of 5·93. Its atomic weight would be about 68; that of gallium is 69·9.
The hypothetical _Eka aluminium_ of Mendelejeff appears therefore to correspond with the gallium of Boisbaudran.
=GALLS.= _Syn._ GALL-NUTS, NUT-GALLS; GALLA (B. P.); GALLÆ (Ph. E.). "Excrescences on _Quercus infectoria_ caused by the puncture and deposited ova of _Diplolepis Gallæ tinctoriæ_." The best galls are blueish-black, heavy, and not yet perforated; intensely astringent. They are imported from Aleppo, and are known in commerce as black or blue galls (GALLÆ NIGRÆ, G. C[OE]RULÆ). The next quality is termed, from their colour, green galls (GALLÆ VIRIDES). Both are gathered before the insect has escaped, and are styptic and powerfully astringent. White galls (GALLÆ ALBÆ) are lighter, less astringent, and inferior.
_Uses, &c._ Galls are extensively employed in the art of dyeing, and constitute one of the principal ingredients in all the shades of black, and are also employed to fix or improve several other colours. A decoction of galls, to which a little green copperas and gum Arabic has been added, forms common writing ink. In _medicine_ they are used as an astringent, in hæmorrhages and fluxes, in doses of 10 to 20 gr.; and topically, under the form of infusion or decoction, as a gargle in relaxation of the uvula; as an injection in gleet and leucorrh[oe]a; as a lotion or fomentation in flabby ulcers, prolapsus ani, &c.; and as an ointment in piles, watery ulcers, &c. The infusion or decoction is also used as an antidote to poisoning by the alkaloids, and was formerly given as a tonic in intermittents. See GALLIC ACID, INK, &c.
=GALL'STONE.= _Syn._ CALCULUS BILIOSUS, C. CYSTICUS BOVINUS, L. Formed in the gall-bladder of neat cattle in winter, when they are fed upon dry food. Used as a yellow pigment, and in medicine--_Dose_, 1 gr.; in dyspepsia and flatulency. Man is also subject to gall-stone, the presence or passage of which is attended with the most acute pain, frequently accompanied with nausea and sickness. In no case should a patient suffering from a paroxysm such as above described delay to seek immediate medical aid. The following treatment is recommended for the benefit of those only who, like emigrants and others, may be unable to obtain professional assistance.
The pain and spasm should be endeavoured to be alleviated by full doses of laudanum, given in soda water. If there be much sickness, the laudanum should be given in the form of an enema. If the paroxysm be excessive, the cautious inhalation of ether or chloroform should be tried. When the pain is of long duration, leeching should be had recourse to. Ice applied freely to the pit of the stomach has sometimes been found to give relief. See CALCULUS.
=GALV'ANIZED IRON.= See IRON and ZINCING.
=GAM'BOGE.= _Syn._ (CAMBOGE; CAMBOGIA, L. B. P.) GAMBOGIA, L. "A gum-resin obtained from _Garcinia Morella_." (B. P.) Gamboge is an active hydragogue and drastic purgative, which occasionally proves useful in torpor of the abdominal and pelvic viscera; but which is highly dangerous in an irritable or inflammatory state of the stomach or bowels, and during pregnancy. It is very apt to induce nausea and vomiting. In large quantities it is a violent poison. "The deaths which have occurred from the use of enormous quantities of Morrison's pills are mainly ascribable to the gamboge contained in those medicines." (Pereira.)--_Dose_, 1 to 5 gr., made into pills or mixture, every 4 to 6 hours; in obstinate constipation, in dropsies, in apoplexy and like cerebral affections, and in worms (especially tape-worm), either alone or combined with other cathartics. See COMPOUND EXTRACT OF COLOCYNTH.
=GAME.= The flesh of game is believed to possess strengthening qualities superior to that of poultry. It also contains less fat. Game is tender and easy of digestion, and it has a delicate and marked flavour. It forms a valuable diet for the invalid, by reason of its easy digestibility.
Respecting the choice and preservation of game, Eliza Acton writes--"Buck venison, which is in season only from June to Michaelmas, is considered finer than doe venison, which comes into the market in October, and remains in season through November and December; neither should be cooked at any other part of the year.
"The greater the depth of fat upon the haunch the better the quality of the meat will be, provided it be clear and white, and the lean of a dark hue.
"If the cleft of the hoof, which is always left on the joint, be small and smooth, the animal is young; but it is old when the marks are the reverse of these.[325] Although the haunch is the prime and favourite joint of venison, the neck and shoulder are also excellent, dressed in various ways, and make much-approved _pasties_. A free current of air in a larder where venison is kept is always a great advantage.
[Footnote 325: Venison is not in perfection when young.]
"All moisture should be wiped daily, or even more frequently, from the venison with soft cloths, when any appears upon the surface, and every precaution must be taken to keep off the flies when the venison is not hung in a wire safe. Black pepper thickly powdered on it will generally answer the purpose.
"Hares and rabbits are stiff when freshly killed, and if young the ears tear easily, and the claws are smooth and sharp. A hare in cold weather will remain good for ten or fourteen days; care only must be taken to prevent the inside from becoming musty, which it will do if it has been emptied in the field. Pheasants, partridges, and other game, may be chosen by nearly the same tests as poultry--by opening the bill the staleness will be detected easily if they have been kept too long by the hardness of the bill. With few exceptions game depends almost entirely for the fine flavour and the tenderness of its flesh, on the time which it is allowed to hang before it is cooked, and it is never good when very fresh; but it does not follow that it should be sent to table in a really offensive state."
=Game, Hashed.= _Ingredients._--The remains of cold game, one onion stuck with three cloves, a few whole peppers, a strip of lemon peel, salt to taste, thickening of butter and flour, one glass of port wine, one tablespoonful of lemon juice, one tablespoonful of ketchup, and one pint of water or weak stock.
Proceed as follows:--Cut the remains of cold game into joints, reserve the best pieces, and put the inferior ones and the trimmings into a stewpan with the onion, pepper, lemon peel, salt, and water or weak stock; stew these for about an hour, and strain the gravy; thicken it with butter and flour; add the wine, lemon juice, and ketchup; lay in the pieces of game, and place them by the side of the fire until they are warmed through, avoiding boiling, otherwise the game will become too hard. Just on the point of simmering serve, and garnish the dish with sippets of toasted bread. _Time._ Altogether, an hour and a quarter.
[asterism] The above recipe applies to any kind of game.
If desirable, the flavour may be varied by adding flavoured vinegars, curry powder, &c.; these, however, cover the gamey taste of the dish, and are, therefore, not to be recommended.
=Grouse, to Roast.= _Ingredients._--Grouse, butter, a thick slice of toasted bread. _Mode._--Let the birds hang as long as possible; pluck and draw them; wipe (but do not wash them) inside and out, and truss them without the head, the same as for a roast fowl. Put them down to a sharp clear fire, keep them well basted the whole of the time they are cooking, and serve them on buttered toast, soaked in the dripping-pan, with a little melted butter poured over them, or with bread sauce and gravy. _Time._ Half an hour; if liked thoroughly done, thirty-five minutes. Seasonable from the 12th of August to the beginning of December. (Mrs Beeton.)
=Hare, Jugged.= _Ingredients._--One hare, a bunch of sweet herbs, two onions, each stuck with three cloves, six whole allspice, half a teaspoonful of black pepper, a strip of lemon peel, thickening of butter and flour, two table-spoonfuls of mushroom ketchup, quarter of a pint of port wine. _Mode._--Wash the hare nicely, cut it up into joints (not too large), and flour and brown them; then put them into a stewpan with the herbs, onions, cloves, allspice, pepper, and lemon peel; cover them with hot water, and when it boils carefully remove all the scum, and let it simmer gently till tender, which will be in about 1-3/4 hour, or longer should the hare be very old. Take out the pieces of hare, thicken the gravy with flour and butter, add the ketchup and port wine, let it boil for about ten minutes, strain it through a sieve over the hare, and serve. A few fried forcemeat balls should be added at the moment of serving, or, instead of frying them, they may be stewed in the gravy, about ten minutes before the hare is wanted for use. Do not omit to serve red-currant jelly with it. _Time._ Altogether, two hours. Seasonable from September to the end of February. (Mrs Beeton.)
=Hare, to Roast.= _Ingredients._--Hare, forcemeat, a little milk, and butter. To be eaten in perfection, the hare must hang for some time. After it is skinned wash it well, and soak it for an hour in warm water to draw out the blood. Make a forcemeat, wipe the hare dry, fill the belly with it, and sew it up. Bring the hind and fore legs close to the body towards the head, run a skewer through each, fix the head between the shoulders by means of another skewer, and be careful to leave the ears on. Put a string round the body from skewer to skewer and tie it above the back. _Mode._--The hare should be kept at a distance from the fire when it is first laid down. Baste it well with milk for a short time, and afterwards with butter; and particular attention must be paid to the basting, so as to preserve the meat on the back juicy and nutritive. When it is almost roasted enough, flour the hare, and baste well with butter. When nicely frothed dish it, remove the skewers, and send it to table with a little gravy in the dish, and a tureen of the same. Red-currant jelly must be served with it. If the liver is good it may be parboiled, minced, and mixed with the stuffing; but it should not be used unless quite fresh. _Time._ A middling-sized hare an hour and a quarter; a large hare one and a half to two hours. (Mrs Beeton.)
=Partridges, to Roast.= Let the birds hang as long as they can possibly be kept without becoming offensive; pick them carefully, draw and singe them, wipe the insides thoroughly with a clean cloth, truss them with the head turned under the wing and the legs drawn close together, not crossed. Flour them when first laid to the fire, and baste them plentifully with butter. Serve them with bread sauce and good brown gravy; a little of this last should be poured over them. _Time._ 30 or 40 minutes. In preparing them for the spit the crop must be removed through a slit cut in the back of neck, the claws clipped close, and the legs held in boiling water for a minute, that they may be skinned more easily. (Eliza Acton.)