406 CARBON AND HYDROGEN. 



Gordon's patent oil gas lamp, the gas is compressed by a force of 30 

 atmospheres, and a limpid fluid* is obtained, which appears to contain 

 several compounds of carbon and hydrogen. If this fluid be heated 

 by the hand, and the vapor condensed into a tube, cooled to 0, it 

 becomes a fluid, which remains such only below 32 Fahr. and 

 even before that temperature is attained, it is reconverted into vapor, 

 which burns with a brilliant flame. Its sp. gr. is 1.9065, very near 

 that calculated for it by Dr. Thomson, before its discovery. It is 

 slightly absorbed by water ; more by alcohol, but is evolved from the 

 latter, with effervescence, by water. At it is again condensed, 

 and the fluid having the sp. gr. of 0.627, is the lightest known. 

 Sulphuric acid absorbs 100 times its volume, and its color is dark- 

 ened, but no sulphuric acid is disengaged. 



Its analysis by oxygen is exactly what was predicted by Dr. 

 Thomson ; as to the quantity of gas required, the carbonic acid pro- 

 duced, the proportions of its constituents, and the equivalent num- 

 ber, as already stated. 



3. Dr. Thomson supposes that the vapor of the fluid distilled from 

 coal tar, and which is, from its similarity to mineral naptha, called by 

 the same names, consists t)f 6 equivalents of vapor of carbon +6 of 

 hydrogen, condensed into 1. Its equivalent number is of course 

 42 ; it requires 6 vols. of oxygen for its complete combustion, and 

 there are produced 6 of carbonic acid. This 'compound is supposed 

 to exist in the coal gases, and as their light is in direct proportion to 

 the quantity of carbon which they contain, it is obvious that upon this 

 view, the vapor of naptha will give three times as much light as defi- 

 ant gas. Its sp. gr. must, of course be 2.9166. In pure naptha, 

 potassium remains unoxidized,. which proves the absence of oxygen. 



4. In the liquid obtained by the condensation of coal gas, Mr. Fa- 

 raday discovered another compound of carbon and hydrogen. This 

 fluid, when recent, boils at 60 Fahr. ; one tenth being exhaled, the 

 boiling point rises to 100, and the whole is not evaporated till it rises 

 to 250. It thus appeared probable that there were different com- 

 pounds, differing in volatility, and by condensing the vapor at differ- 

 ent temperatures, he attempted to obtain them separate. The boil- 

 ing point appearing more constant between 176, and 195, than 

 any where else, he carried on the distillation within those limits, and 

 by repeating it, and condensing the vapor at 0, he obtained a fluid 

 which he called bi-carburet of hydrogen. 



Its properties are as follows ; it is a transparent colorless fluid, 

 smells like oil gas, or almonds; at 60, sp. gr. .850, and that of its 

 vapor 2.776. At 32, it becomes solid and crystalline ; at trans- 

 parent and crumbles into grains, having nearly the hardness of loaf 



* About 1 gallon for 1000 cubic feet of good gas. Phil. Trans. 1825, p. 441. 



