DESTRUCTIVE DISTILLATION OF ANIMAL MATTERS. 595 



The formation of ammonia during this decomposition was demonstrated by 

 distilling the acid nitrate from the red substance with potash. The distillate, 

 which had the smell of ammonia contaminated with an empyreumatic odour, 

 and sometimes with that of picoline, was saturated with hydrochloric acid, and 

 evaporated with excess of bichloride of platinum to nearly complete dryness. 

 Octahedral crystals of platinochloride of ammonium were deposited, which were 

 examined under the microscope, and found to be free from any other salt. 



The quantity of pyrrol contained in bone-oil is far from inconsiderable, and 

 now that its properties have been investigated, it is easy to see that a great deal 

 must have been destroyed during the treatment by which the crude bases were 

 extracted. As my previous investigation of the picoline from coal-tar had shown 

 that its neutral sulphate is converted into bisulphate by boiling, I took care to 

 add to the crude sulphates extracted by agitating bone-oil with sulphuric acid, a 

 large excess of acid before boiling it for the purpose of separating pyrrol ; and 

 in this way large quantities of the red matter in an impure state were produced 

 during the early part of the investigation. It was only after I had advanced 

 some way in the investigation that the cause of its formation became in- 

 telligible, and the crude sulphates were then distilled without the addition 

 of acid, and the pyrrol mixed with empyreumatic oils and bases of the pico- 

 line series was obtained in quantity sufficient for investigation. The diffi- 

 culty experienced in removing the last traces of pyrrol from the bases was very 

 great, and it was necessary to boil the solution for several days ; but I have now 

 found that oxidizing agents, such as nitric acid, or, still better, bichromate of 

 potash, offer invaluable means of purification, as they decompose the pyrrol with- 

 out producing the slightest effect on the bases. 



In the present and preceding parts of this investigation, I have directed atten- 

 tion to the basic constituents of bone-oil. In the next part, I propose to treat of 

 its non-basic constituents, in the investigation of which some progress has already 

 been made. In particular, it has been found that, by repeated rectifications, a 

 fine volatile fluid, boiling as low as 150° Fahr., is obtained. This oil consists of 

 at least two different substances, separable by means of a freezing mixture, 

 which causes the fluid to divide into two perfectly distinct strata, with a well- 

 marked line of separation. The higher fractions do not present this peculiarity, 

 but they are also complex, containing benzene, and apparently some of its homo- 

 logues, along with the alcohol radicals of the fatty series, and also nitrogenous 

 compounds decomposable by alcoholic solution of potash and by sodium. 



VOL. XXI. TART IV. 7 X 



