78 M. Boussingault on the Composition of Bitumens. 



The only contradictory fact opposed to this conclusion is that 

 recorded by M. de Humboldt, when he states, that at La Punta 

 d'Araya, in the Gulf of Cariaco, he saw petroleum issuing 

 from mica-slate. 



The bitumen of Bechelbronn is viscid, of a very deep brown 

 colour. The uses to which it is applied have procured for it 

 the name of mineral grease. 



Heated to 120, this bitumen does not yield any product ; 

 but, on distilling it with water, an oily principle is procured, 

 which is volatile, of a pale yellow colour, and in which analysis 

 shews there is nothing else than carbon and hydrogen. As this 

 carburetted hydrogen appears to constitute the principal liquid 

 of bitumens, the author designates it by the appellation Petro- 

 line. 



Petroline boils at 280 of the mercurial thermometer ; its 

 odour is that of bitumen ; at 21 its weight is 0.891 , even at a 

 cold of 18 it does not lose its fluidity ; alcohol dissolves it in 

 small quantity, and it is much more soluble in ether. It con- 

 tains carbon 0.885, hydrogen 0.115, and is consequently isome- 

 ric with the essential oils of turpentine, lemon, and copaiba. 



By using the methods employed by M. Dumas, it is found 

 that the density of the vapour of petroline is equal to 9.415, 

 whilst calculation indicates 9.538. This is precisely double the 

 weight of the vapour of the essence of turpentine. If we ad- 

 mit that four volumes of vapour constitute an atom of petroline, 

 its atomic composition will be as follows : 



Carbon, 80 atoms, . . 3060.8 

 Hydrogen, 64 atoms, . . 400.0 



3460.8 



Independent of the petroline, there exists in the bitumen a black 

 solid substance, which is absolutely insoluble in alcohol, and 

 soluble in ether. M. Boussingault names this product Asplial- 

 tine, because it forms the base of that species of mineral which 

 mineralogists describe under the name of asphaltum. 



AspUaltine may be procured by subjecting bitumen puri- 

 fied by ether to the continued action of a temperature of 

 240 or 250. Asphaltum is solid, very black and brilliant, its 



