PRESENT STATE OF THE CHEMISTRY OF GAS-LIGIITING. 
285 
volume of butylene contains two volumes of carbon vapour and four of hydrogen. It is 
a large constituent of oil gas, and it exists in cannel gas to the extent of about from 3 
to 4 per cent. Common gas contains it in very small proportions. The gas is colour¬ 
less, and it has a peculiar odour. Its action on the body is not known, but no doubt it 
is anaesthetic, like the other hydrocarbons of this series. It is nearly twice as heavy as 
atmospheric air, its gravity being 1-935; and therefore 100 cubic inches weigh just 60 
grains. It burns, as you perceive, with a long sooty flame, the jet being nearly four 
times as long as the comparison jet of coal gas; and the illuminating power of it is 
about four times as great as the jet of common gas. A cubic foot of the gas requires 6 
cubic feet of oxygen, or 30 cubic feet of air, to burn; and the products of its combus¬ 
tion are 4 cubic feet of carbonic acid and much aqueous vapour. Like the other hydro¬ 
carbons, it is but slightly soluble in water, but it is freely dissolved by alcohol and by 
the fixed and volatile oils; olive oil, for example, absorbs about six times its volume 
of the gas. It is also absorbed by chlorine and bromine, forming compounds analogous 
to Dutch liquid ; and it is likewise freely absorbed by sulphuric acid, a volume of the 
acid taking up 100 volumes of the gas. If it is passed through a red-hot tube, it is de¬ 
composed and resolved into marsh gas, hydrogen, and carbon. It is also easily condensed 
by cold and pressure, forming a thin, transparent, and colourless oil, of which I show 
you a specimen. In the days of oil gas, when the Compressed Gas Company was in 
existence, this ethereal oil was produced in rather large quantity ; 1000 cubic feet of the 
gas submitted to a pressure of 30 atmospheres produced about a gallon of oil, composed 
almost entirely of butylene, with benzole and an oil of doubtful composition. It was 
from this mixture that Faraday obtained butylene. 
(e) Acetylene, or Klumene (C 4 H 2 ). A volume of this gas contains its own volume 
of carbon vapour and one volume of hydrogen. The gas exists in but very small pro¬ 
portions in coal gas ; and it is remarkable as being a hydrocarbon which can be obtained 
by the direct union of carbon with hydrogen, by igniting carbon, by the aid of electricity, 
in an atmosphere of hydrogen. It can also be obtained by exposing a mixture of car¬ 
bonic oxide and marsh gas to the action of a high temperature,—a circumstance which 
may hereafter be of practical utility in the manufacture of gas. It is likewise a product 
of the decomposition of hydrocarbons by heat. The gas is colourless, with a peculiar 
odour, and it is probably anaesthetic. It is a little lighter than air, the specific gravity 
of it being 0-8^8; 100 cubic inches therefore weigh just 28 grains. It burns with a 
brilliant light, as you here perceive, and with a sooty flame, considerably longer than 
the flame of coal gas ; and when I mix it with a large volume of hydrogen gas, it still 
burns with a bright flame. A cubic foot of the gas requires 2| feet of oxygen, or 12£ 
feet of air, to burn it; and it produces two volumes of carbonic acid, and aqueous vapour. 
The gas is freely absorbed by water to the extent of its own bulk, and it is again ex¬ 
pelled unchanged when the water is boiled. It also combines, with great energy, with 
chlorine, bromine, and sulphuric acid. The best absorbent for it is a solution of ammo- 
nio-subchloride of copper. The solution is made by mixing a dilute solution of chloride 
of copper with an equal bulk of pure muriatic acid, and shaking the mixture in a bottle 
with copper filings, or boiling it with copper turnings until it is colourless. The solu¬ 
tion is then put into a bottle or flask, with three tubes adapted to it: one for delivering 
the coal gas into the solution, a second for the exit of the gas, and the third for pouring 
in a strong solution of ammonia. When the gas has displaced all the air from the bottle, 
ammonia is poured into the solution until a deep blue liquid is obtained; and this, as 
you here see, absorbs the acetylene of the gas, and produces a chocolate or reddish-brown 
precipitate of acetylide of copper (C^HjCu^, which is a compound in which two pro¬ 
portions of copper have replaced one of hydrogen. This acetylide of copper is to be 
collected on a filter, washed with water, and dried. If it is heated in a flask, as I am 
now doing, with dilute muriatic acid, it is decomposed, and the acetylene escapes with 
effervescence. You will notice, too, with what a bright yellow flame the gas burns. 
(f) Benzole, or, as it is sometimes termed, Benzine, Phene, or Bicarburetted Hydrogen 
(C 12 H 6 ). One volume of this vapour contains three volumes of carbon vapour and three 
of hydrogen. It exists in coal gas in very variable proportions. At times it is but barely 
discoverable, and at other times it is present in large quantity. It is often present in 
London gas to a considerable extent, and I attribute it to the practice which 'is occa¬ 
sionally followed of pouring light naphtha into the mains for the purpose of removing 
paphthaline. I here show you a specimen of nitro-benzole obtained from only 15 cubic 
