Chap. I.] Analyfis of Volatile Animal Oil. 77 



remains behind with the earthy matter. Lavoifier, 

 after having treated of the decompofition of vegetable 

 matter, obferves: 



< Animal fubftances, being compofed nearly of the 

 fame elements with cruciferous plants, give the fame 

 produces in diilillation, with this difference, that,/ as 

 they contain a greater quantity of hydrogen and azote, 

 they produce more oil and more ammoniac. I^fhall 

 only produce one fact, as a proof of the exactnefs 

 with which this theory explains all the phenomena 

 which occur during the diftillation of animal lub- 

 itances which is the rectification and total decom- 

 pofition of volatile animal oil, commonly known 

 by the name of Dippel's oil. When thefe oils are 

 procured by a firft diftillation in a naked fire, they are 

 brown, from containing a little charcoal almoft in a 

 free ftate ; but they become quite colourlefs by recti- 

 fication. Even in this ftate the charcoal in their com- 

 pofition has fo flight a connection with the other ele- 

 ments, as to feparate by mere expofure to the air. If 

 we put a quantity of this animal oil, well rectified, 

 and conicquently clear, limpid, and tranfparent, into a 

 bell-glafs filled with oxygen gas over mercury, in a 

 fhort time the gas is much diminilhed, being abforbed 

 by the oil ; the oxygen, combining with the hydrogen 

 of the oiJ, forms water, which finks to the bottom ; at 

 the fame time the charcoal which was combined with 

 the hydrogen being fet free, manifefts itfelf by ren- 

 dering the oil black. Hence the only way of preferr- 

 ing thefe oils colourlefs and tranfparent, is by keeping, 

 them in bottles perfectly full, and accurately corked, 

 to hinder the contact of air, which always difcolours 

 them. 



c SuccefTive rectifications of this oil furnilh another 

 phenomenon confirming our theory. IG each diftil- 

 lation 



