CARBURETTED HYDROGEN. 401 



b. The gas distilled from mineral coal after purification with li- 

 quid potash to remove the carbonic acid, and with chlorine* to re- 

 move the olefiant gas, is also sufficiently pure, and probably the same 

 would hold nearly true of the gases obtained by heating the follow- 

 ing substances. 



(c.) Anthracite of Pennsylvania and of Rhode Island, the latter 

 moist ;f kernels of the hickory nut, and of other oleaginous nuts and 

 seeds ; common woods, as oak, and maple, pine and pine knots ; tar^ 

 tar ; recent bone ; moist charcoal ; acetate of lead, and acetate of 

 copper ; spermaceti ; tallow, wax, &c. 



(c?.) In these mixed gases, there are variable proportions of car- 

 bonic acid of olefiant, and perhaps sometimes of super-olefiant gas, 

 and various vapors. 



2. PROPERTIES OF LIGHT CARBURETTED HYDROGEN GAS.J 



(a.) Colorless and tasteless, not absorbable by water, which, how- 

 ever, after having been previously boiled, takes up about V f ^ 

 volume. 



(b.) Odor slight when it is otherwise, it is derived from mixture 

 with other gases and vapors, especially when the gas is distilled from 

 bituminous coal. 



(c.) Sp. gr. .555, air being 1 ; consequently, 100 cubic inches 

 weigh, at mean temperature and pressure, 16.944 grains, just half 

 as much as oxygen gas. Its sp. gr. is thus obtained by calcula- 

 tion; it consists of 1 vol. vapor of carbon, which weighs .4166-f 2 

 vol. of hydrogen, .0694x2 = . 1388 = . 555, which is exactly the 

 weight of carburetted hydrogen obtained by experiment. 



(d.) Extinguishes burning bodies, but is itself inflammable ; burns 

 from a jet, with a flame, which is yellow or variously tinged; its 

 power of illuminating is much greater than that of hydrogen gas. 



(e.) Mixed with from 6 to 12 volumes of atmospherical air, it ex- 

 plodes with violence by contact of a lighted taper. 



(f.) More violently with oxygen gas the latter must exceed the 

 inflammable gas in volume, but must not be over two and one fourth 

 times its bulk. 



(g.) Loses its combustibility, if rarefied, so that the pressure is less 

 than one fourth part that of the atmosphere. 



* Chlorine has the property of removing the heavy species of carburetted hydro- 

 gen, to form with it a peculiar compound, the chloric ether, which has been regard- 

 ed, but erroneously, as an oil. This property of chlorine must be repeatedly men- 

 tioned in giving the account of the carburetted hydrogen gases, and will be again 

 illustrated In its proper place. t See Am. Jour. Vol. X, p. 331. 



t That obtained from the marshes is the purest variety. 



For carbonic acid has the sp. gr. 1.527, from which deduct that of the 1 vol. of 

 oxygen which it contains, 1.111, which leaves .416 for the weight of the carbon in 

 vapor. 



51 



