HYDRO-CARBON. Hydrogen and carbon combine in a great many different proportions, forming compounds many of which possess considerable interest. It rarely happens, however, that these compounds can be obtained synthetically by actually mixing the ingredients ; they are in general produc,ed by the decomposition of organic matters.
Some of the pfincipal hydro-carbons are as follows ; Light-carburetted hydrogen . . = C H2 Olefiant gas . . . . = C2 H2 Bic,arbide of hydrogen . . , = C6 He Etherine . . . , - . = C4 114 Naphtha . . , . . = Ce H5 Naphthalin . , , . = Cio 114 and aLso common coal gas, oil gas, resin gas, coal tar, and many analogous substances.
The characteristic properties of the hydro-carbons are their combustibility, and the energy with which they are in general decomposed by chlorine w.hen exposed to light, the result being the production of hydrochloric acid, and the liberation of carbon. Some of the hydro-carbons are isomerio, and yet possess distinctive peculiarities.
Light-carburetted hydrogen may be produced artificially, by mix ing 40 parts crystallized acetate of soda, 40 parts solid hydrate of potass, and 60 parts of powdered quick lime. When this mixture
is strongly heated in a retort, the gas passes over, and may be collected over wat,er. It is the fire damp of coal mines, and the marsh damp which proceeds from stagnant and decomposing mud.
Common coal gas is composed chiefly of carbon, hydrogen, and ,.111 r, and is produced by the destructive distillation of coal, the .t ile substances passing over, and coke remaining in the retort..
• olatile matters are first passed through a condenser kept cold 1,v immersion in water, and here the water, tar, ammoniacal liquor and other condensable vapours are retained. The gases which pass over, and which consist chiefly of carburetted hydrogen, hydrogen, sulphuretted hydrogen, carbonic oxide, carbonic acid, nitrogen, and cyanogen, are then passed through a mixture of quick lime and water in a vesAl called a purifier, by which a large portion of the sulphur etted hydrogen and carbonic acid are absorbed; the remaining mixed gases are then sufficiently pure for the ordinary purposes of illumina tion.
Olefiant Gas, and Naphtha are described in their proper places ; q. v.