MABERY. — CONSTITUENTS OP PETROLEUM. 135 



of purification aud by the higher specific gravity. In the case of this 

 particular hydrocarbon, the method of purification is not especially men- 

 tioned, but their general method, which is mentioned under nearly every 

 other member of the long series of hydrocarbons which they examined, 

 consisted in agitating the oil in the cold with concentrated sulphuric acid 

 and washing with sodic carbonate. Then their method included no 

 special means of drying the oil for analysis. It is quite impossible to 

 remove moisture entirely from these hygroscopic oils without the aid 

 of the most vigorous desiccating agents. Nothing less than standing 

 continuously over sodium, in my experience, will insure a perfectly 

 dry condition. 



It is evident from the following description of their experiments that 

 Pelouze and Cahours tried the action of reagents on their oil, although 

 they seem not to have suspected the presence of an aromatic hjdrocarbon 

 Q,H2«-6: "Le brome, I'acide azotique fumant, I'acide sulfurique au maxi- 

 mum de concentration, I'acide azotique de Nordhausen ne I'attaquent pas 

 a froid. Le melange des acides azotique et sulfurique agit sur le car- 

 bure lorsqu'on maintient ces corps pendant quelque temps en ebullition. 

 Prolonge Ton Faction, on voit se former une petite quantite d'un 

 produi:; solide et cristallisable. II se separe en meme temps une huile 

 jaunatre un peu plus dense que I'eau. De plus, on demele dans les 

 vapeurs nitreuses Todeur caracteristique des acides volatils homologues 

 de I'acide acetique." 



Upon agitation with nitric and sulphuric acids, the distillate 190°-191° 

 deposited a heavy nitro compound. 



Our observations concerning the action of a mixture of concentrated 

 nitric and sulphuric acids in the cold on this distillate do not coincide 

 with those of Pelouze aud Cahours. Immediately upon vigorous agita- 

 tion, a heavy nitro compound separated as a heavy oil, forming a crystal- 

 line product on standing. 20 grams of the oil lost 4.5 grams by this 

 treatment, equivalent to 22 per cent of its weight. The nitro compound 

 was very sparingly soluble in hot alcohol, from which it crystallized in 

 needles, melting at 169°-170°. As will be seen later, nitro compounds 

 with the same melting point were separated from Ohio and Canadian 

 petroleum, which do not correspond in melting point to that of either 

 dinitrodurol, 205°, nor of dinitroisodurol, 156°, although crystallization 

 was continued until the melting point was pretty constant. It would 

 have been interesting to obtain sufficient of this substance for more com- 

 plete examination ; but, with the great amount of work on hand in con- 

 nection with the principal hydrocarbons, it did not seem best to allow our 



