Cooley's Cyclopaedia of Practical Receipts Volume I Part 258

=Gargle of Verd'igris.= _Syn._ GARGARISMA aeRUGINUS, G. CUPRI ACETATIS, L.

_Prep._ (Guy's Hosp.) Oxymel of verdigris, 4 dr.; honey of roses, 2 oz.; barley water, 3-1/2 fl. oz. Used as a detergent for ulcers in the throat.

If swallowed it produces violent vomiting. The addition of 2-1/2 oz. of water to the above produces a gargle sufficiently strong for most cases.

=Gargle of Vin'egar.= See GARGLE OF ACETIC ACID.

=Gargle of Zinc.= _Syn._ GARGARISMA ZINCI, G. Z. SULPHATIS, L. _Prep._ (Dr Copland.) Sulphate of zinc, 20 gr.; oxymel, 1 fl. oz.; rose water, 7 fl.

oz. In aphthous sores, relaxations, ulceration of the tonsils, &c.

=GAR'LIC.= _Syn._ ALLIUM, L. The _Allium sativum_ of botanists. It is diaph.o.r.etic, diuretic, expectorant, stimulant, and tonic; and externally, irritant, rubefacient, and even vesicant.--_Dose_, 1/2 dr. to 1-1/2 dr.; in enfeebled digestion, chronic diarrha, old chronic coughs, atonic dropsies, and worms. An antispasmodic and counter-irritant liniment is made of the juice, which was formerly esteemed in chest diseases and infantile convulsions. A small clove of garlic, or a few drops of the juice, was formerly introduced into the ear in certain forms of deafness.

As a condiment its properties resemble those of the onion, than which it is much more powerful.

=GAR'NET.= In _mineralogy_, one of the precious stones or gems. The finest specimens of n.o.ble garnet (SYRIAN or ORIENTAL GARNET) are brought from Pegu. According to chemical a.n.a.lysis, the garnet is a double silicate of alumina and lime, coloured with iron and manganese.

=Garnet, Facti"tious.= See PASTES.

=GA'RUM.= [L.] A species of pickle or sauce prepared of fish, in a state of incipient putrefaction, strongly salted and seasoned with aromatics.

According to Pliny, the Romans used a species of lobster for this purpose.

=GAS.= _Syn._ GAZ, Fr. A permanently elastic aeriform fluid. In English the term 'air' is now usually restricted to the gaseous mixture forming the atmosphere, but it was formerly used as a synonym for 'gas.' The princ.i.p.al gases are the elementary bodies hydrogen, chlorine, oxygen and nitrogen, and the compounds ammonia, carbonic acid, carbonic oxide, carburetted hydrogen, hydrochloric acid, phosph.o.r.etted hydrogen, protoxide of nitrogen, sulphuretted hydrogen, and sulphurous acid. See these substances under their respective heads.

=Gas.= _Syn._ COAL GAS, ILLUMINATING G. The term 'gas' is popularly applied to the important mixture of hydrocarbons produced by the destructive distillation of pit-coal, and now employed as a source of artificial light in most of large towns of Europe and America. Although artificial illumination by means of coal-gas was, previous to 1819, used in Great Britain in isolated cases, and had been employed for the occasional lighting up of the mansion of Culrose Abbey in Scotland, by Lord Dundonald, as far back as 1787; and by Murdoch, in 1798, for lighting the foundry of Boulton and Watts in Soho, it does not appear to have been generally adopted in London, and the other large towns of England and Scotland until that year; since which time to the present artificial gas illumination has steadily progressed, and increased to so enormous an extent, that some works are now delivering millions of cubic feet of coal-gas a day. The apparatus used in the manufacture of gas on the large scale consists essentially of a system of closed retorts (_a_) of cast iron or fire-clay, generally having the form of a flattened cylinder, and arranged in sets of three or five, and heated by the same coal fire, as shown in the accompanying drawing.

[Ill.u.s.tration]

The quant.i.ty of coal required to charge each retort is about two bushels, and it takes about four hours for the coal to give off all its gas. When it has done this the resulting c.o.ke is removed from the retort, and a fresh charge of coal is thrown into it, the mouth of the retort being then closed with a thick iron plate, and luted with clay. An iron pipe ascends from the upper side of the front of the retort, projecting from the furnace, and after describing a curve at its upper extremity, this iron pipe opens into a much wider tube, called the _hydraulic main_ (_b_), which latter pa.s.ses horizontally along the front of the range of furnaces, the tubes from all the retorts dipping into it. The hydraulic main is always kept half full of the water and the tar which condenses from the ascending gas; owing to which arrangement the opening into each retort is effectually closed by a water-valve, and thus permits a fresh charge of coals to be thrown in, and of c.o.ke to be withdrawn in any one or more of the retorts, without interfering with the distillation going on in the others.

The aqueous portion of the liquid deposited in the hydraulic main, which is known as the _ammoniacal liquor_, and forms the princ.i.p.al source of the commercial salts of ammonia, consists princ.i.p.ally of solution of carbonate of ammonium, but contains also sulphide, cyanide, and sulphocyanide of ammonium. After it leaves the hydraulic main, the gas pa.s.ses into the _condenser_ (_e_), which is composed of a series of bent iron tubes (shown in the plate), these being kept cool either by the large surface they expose to the air, or, if necessary, by means of a stream of cold water applied to the outside.

Any of the volatile hydrocarbons or salts of ammonia escaping condensation in the hydraulic main are arrested in the condensers, but not always; hence it is necessary to afterwards carry the gas through a _scrubber_ (not figured in the plate) or case containing pieces of c.o.ke, over which a stream of water being made to trickle, absorbs any remaining ammoniacal vapours. The gas next pa.s.ses through the _lime purifier_ (_f_), an iron box fitted with shelves, on which is placed slaked lime, which absorbs the carbonic acid, and part, but not the whole of, the sulphuretted hydrogen contained in the gas. Of the many methods devised for the removal of the sulphuretted hydrogen, none appears to be so successful and economical as that which consists in pa.s.sing the gas over a mixture of sulphate of iron, slaked lime, and sawdust.

The gas, after it has become purified by the foregoing processes, is pa.s.sed into the gasometer (_g_) (part of which is represented in the plate), whence it pa.s.ses into the mains, by which it is conveyed to the various condensers. Another prejudicial impurity formed in gas is carbon disulphide, which when burned gives rise to small quant.i.ties of sulphuric acid, and this in time attacks certain kinds of furniture, as well as the bindings of books.

Dr Angus Smith effects the removal of the disulphide by pa.s.sing the gas through a solution of plumbic oxide in caustic soda, diffused through sawdust.

The quality of coal-gas is largely dependent upon the temperature employed in its manufacture. If the retorts are insufficiently heated, the result will be the formation of certain easily-condensable hydrocarbons, which not only diminish the bulk of the gas, but cause considerable inconvenience by collecting in and blocking up the pipes. On the contrary, should too much heat be used, the gas becomes partially decomposed by contact with the red-hot retort, and deposits on its sides the substance known as "gas carbon," thus not only removing to a certain extent the const.i.tuent to which the gas owes its illuminating power, but impoveris.h.i.+ng its lighting qualities still more, by diluting it with an unnecessary quant.i.ty of liberated hydrogen. These latter effects are forcibly ill.u.s.trated in the following a.n.a.lysis of the gas collected from Wigan cannel coal at different periods of the distillation.

The best gas is said to be produced when the retorts are heated to a bright cherry red.

In 100 Volumes. 1st Hour. 5th Hour. 10th Hour.

Olefiant gas and volatile hydro-carbons 130 70 00 Marsh gas 825 560 200 Carbonic oxide 32 110 100 Hydrogen 00 213 600 Nitrogen 13 47 100

"The value of gas as an illuminating agent may be said to depend on the amount of hydrocarbons present, and on the relation which the carbon bears to the hydrogen in these substances. In marsh gas, CH_{4}, which is, practically speaking, non-luminous, the per-centage composition is, carbon 75, and hydrogen 25. In olefiant gas, C_{2}H_{4}, the carbon is 857, and the hydrogen 143, and the gas possesses a correspondingly greater amount of illuminating value. In acetylene, C_{2}H_{2}, we have a gas of still greater illuminating value, the proportion of carbon to hydrogen being also greater, the per-centage composition being, carbon 923, and hydrogen 77. In benzol, C_{6}H_{6}, we have the same per-centages; while in naphthalene, C_{10}H_{8}, a still higher ratio between the carbon and hydrogen exists, and a corresponding increased value in light-giving power. It was formerly taken as an axiom that the illuminating value of a mixture of gases was also proportionate to the relation between the carbon and hydrogen, but although this is very good as a rough criterion in practice, the statement must not be accepted as strictly true. The illuminating power of a mixture of gases is known now to depend far more on the nature of the particular compounds present, than upon the absolute proportion between the hydrogen and carbon; for while on the one hand it is possible to have a gas (marsh gas) containing as much as 754 per cent.

of carbon, and yet which is valueless for illuminating purposes; it is also possible to have a mixture of gases in which the per-centage of carbon is far less, although the illuminating value is much greater."[326]

[Footnote 326: 'Chemistry, Theoretical, Practical, and a.n.a.lytical,'--Mackenzie.]

Coal gas consists of a mixture of the following bodies:

Marsh gas (light carbonetted hydrogen).

Olefiant gas (heavy " " ).

Hydrogen.

Carbonic oxide.

Nitrogen.

Vapours of liquid hydro-carbons.

Vapour of bisulphide of carbon.

The yield of gas, and also the illuminating power of the product, vary greatly with different kinds of coal. The average yield may be roughly estimated at 10,000 cubic feet of gas per ton of coal.[327]

[Footnote 327: For practical details respecting the manufacture of this product, see the article COAL GAS in 'Ure's Dictionary of Arts, Manufactures, &c.,' 'Wagner's Chemical Technology,' and 'Chemistry, Theoretical, Practical, and a.n.a.lytical.']

Anthracite is by no means suited for a gas coal. The best coals for this purpose are those which are bituminous; they comprise caking coal, parrot coal, and certain varieties of cannel coal. London gas (which is generally deficient in illuminating power) is manufactured princ.i.p.ally from Durham and Newcastle coal.

In addition to the elementary composition of the coal, the amount and nature of the volatile matter contained in it is an important factor in its value as a source for gas. It should also yield a small amount of ash, and be as free as possible from sulphur, besides which its ultimate a.n.a.lysis should show a comparatively small proportion of oxygen. If there be an excess of this latter element, the production of the hydrocarbon illuminants will be diminished, since the hydrogen which would go to their formation would unite with the oxygen to form useless water.

The late Charles Mansfield proposed to increase the illuminating power of ordinary coal-gas, and to render water gas or even atmospheric air luminiferous, by pa.s.sing them through sponges or over trays containing mineral naphtha or benzole; and a patent was taken out for this purpose.

The gas so treated imbibes or dissolves a portion of the liquid, and burns with increased brilliancy. The method of saturating the gas with the liquid hydrocarbon is as follows:--"The apparatus consists of a bra.s.s reservoir or chamber attached to the end of the gas-pipe, near the burner.

This reservoir may be in the shape of an oil-flask, made air-tight, with a screw-joint, or other means of supplying any highly volatile oil, turpentine, or mineral naphtha, and should be kept about half full. Into this reservoir the gas-pipe ascends a little above the surface of the oil; a very small jet-pipe of gas, regulated by a stop-c.o.c.k, is branched off below this chamber, to supply a minute flame, so as to cause a sufficient evaporation from the oil to unite with the gas in the flask receiver. The whole is, of course, surmounted with the usual burner and lamp-gla.s.s."

The naphthalising of gas did not work well on a large scale. Recently, however, an attempt was made to get up a company in England to work a French patented process, which differed only from that of Mansfield's in the subst.i.tution of another hydrocarbon (probably a petroleum product) for benzol. The chemical and technical journals exposed this invention, and prevented the sinking of capital in a worthless undertaking. On a small scale, simple 'naphthalisers' appear to work very well.

The illuminating power of gas, as well as of other sources of light, may be directly ascertained by what is termed the 'comparison of shadows,' or indirectly, and more conveniently, by chemical a.n.a.lysis.[328] See AIR GAS, ILLUMINATION.

[Footnote 328: See 'Watts's Dictionary of Chemistry,' vol. i.]

=GASTROPHAN= (Apotheker J. Furst, Prague). For strengthening the digestion and improving the appet.i.te. Qua.s.sia, 30 grammes; orange berries, 15 grammes; galangal, 4 grammes; cardamoms, 2 grammes; star anise oil, 10 drops; orange-peel oil, 10 drops; spirit, 180 grammes; water, 120 grammes; digested and filtered. (Hager.)

=GASTROPHILE= (Dr Borchard). There are several numbers of this preparation. Soda water, containing common salt, perhaps in some of the numbers mixed with Glauber's salts.

=GAZ'OGENE.= [Fr.] _Syn._ AeRATING MACHINE. A portable apparatus for aerating water and other liquids. Many forms have been given to this instrument, but in all the principle is the same. Powders for generating carbonic acid gas are placed in a separate compartment, and the liquid to be aerated in another. The two compartments are connected by a suitable tube, and a second tube, furnished with a spring tap, affords an exit for the aerated liquid. By the aid of the gazogene, water, wine, ale, &c., may in a few minutes be fully saturated with carbonic acid gas, and so rendered brisk and piquant. By using fruit syrups, manufactured from English and foreign fruits, the most delicious aerated summer beverages can be made, resembling those so much esteemed by travellers in the South of Europe and the sea-board cities of the Western world.

The following are the proportions of soda and acid required for charging gazogenes:

For 2 pints, powdered tartaric acid, 280 grains; bicarbonate of soda, 340 grains.

For 3 pints, powdered tartaric acid, 340 grains; bicarbonate of soda, 420 grains.

For 5 pints, tartaric acid, 620 grains; carbonate of soda, 760 grains.

Put the acid and soda in different coloured papers.

=GEDACHTNISS-LIMONADE--Mnemonic Lemonade= (manufactured by G. M. Raufer, Vienna). A mixture of 15 parts phosphoric acid, 15 parts glycerin, 70 parts water. (Schadler.)

=GEHOR INSTRUMENT.= Instrument for deafness (Apotheker F. Brunner, Troppau). A little tube of silver plate, 2 centimetres long and as thick as a straw, with a small mussel-shaped widening at one end, which is wrapped in cotton wool, to be inserted in the ear.

=GEHOR LIQUOR=, Schweizer--Swiss Cure for Deafness (Raudnitz). Water mixed with a little coa.r.s.e brandy. (Wittstein.)

=GEHOROL--Oil for Deafness= (C. Brockelmann, Soest). Provence oil adulterated with sunflower oil and mixed with very small traces of camphor and cajeput, sa.s.safras, and rosemary oils. (Hager.)