illuminating power) is manufactured principally 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 analysis 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 passing 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 brass 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-cock, 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-glass.”
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 substitution 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 analysis.[328] See Air Gas, Illumination.
[328] See ‘Watts’s Dictionary of Chemistry,’ vol. i.
GASTROPHAN (Apotheker J. Fürst, Prague). For strengthening the digestion and improving the appetite. Quassia, 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. Aërating Machine. A portable apparatus for aërating 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 aërated 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 aërated 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 aërated 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: