-tSS M. Boussingault o?i the Constitutio7i of Bitumens. 



tiii|jentine, citron, and copaiva. Its vapour, calculated by Dumas' 

 process, is equal to y'4>lo, which is double that of the essential oil of 

 turpentine. Supposing that 4 vols, of vapour constitute 1 eq. of pe- 

 trolene, its composition will be 



Carbon, SO eqs. = 480 



Hydrogen .... 64 eqs. = 64 — 544 

 Besides petroletie, there exists in this bitumen a black substance 

 which remains after the separation of the petrolene : this is the solid 

 principle of bitumen. It is very brilliant, of a conchoidal fracture, 

 and is heavier than water ; at about .570" Fahr. it becomes soft and 

 elastic ; it decomposes before it fuses, and burns like the resins, leav- 

 ing a large quantity of coke. The author has called this substance 

 asphaltene, from its forming the base of the minerals which mineralo- 

 gists describe under the name of asphalt. Asphaltene may be pro- 

 cured by submitting bitumen purified by aether to a prolonged heat of 

 about 470° Fahr. It is insoluble in alcohol, but aether, the ti.xed oils, 

 and oil of turpentine dissolve it. It is composed of 



Carbon 75'3 



Hydrogen 9'9 



Oxygen 14-8 -100- 



and maybe represented by the formula C^o H'- O', or by C""" H'^* O'', 

 which indicates that asphaltene results from the oxidation of petro- 

 lene. 



The bitumen of Bechelbronn purified by aether may then be consi- 

 dered as a mixture of petrolene and asphaltene, at least this is the re- 

 sult of analysis. It contains 



Carbon 87-0 



Hydrogen 11-2 



Oxygen 1-8— 100- 



It would then appear that the viscid bitumens are mixtures, probably 

 in various proportions, of two substances, w!;ich may be separated, 

 and each of which has a definite composition. One of these principles 

 (asphaltene), solid and fixed, resembles asphalt; the other (petrolene), 

 liquid, oily, and volatile, approaches, in some of its properties, to some 

 varieties of petroleum. From this it will be seen that the consistence 

 of bitumens depends on the predominance of one or the other of 

 these principles in the mixture. 



The analogy existing between asphaltene and asphalt has induced 

 the author to examine whether their respeclive composition is the 

 same. In consequence of this he analysed the asplialt of Coxitambo, 

 which may be taken as a type of the species. This asphalt has a 

 conchoidal fracture, and is of a brilliant lustre ; its density is 1 -68 ; 

 it is dissolved by petrolene and the fixed oils with much greater diffi- 

 culty than artificial asphaltene. Exce])t this difference, which may 

 arise from the cohesion of the particles of the native asphalt, the cha- 

 racters of these two substances are identical. It decomposes before 

 it fuses, and burns, leaving O'0 16 of a slightly ferruginou.s ash. It 



consists of Carbon 75*0 



Hydrogen 9'3 



Oxygen 15-5—100. 



Nute. — This analysis would indicate the elementary composition of 

 native asphalt, and the artificial asphalt obtained b^ M. Boussingault, 

 to be the same. 



