ivhen treated 'itith Nitric Acid. 3^7 



quid^-they submitted the fibrous residue to the following 



Boilincr water was rendered yellow by it, and acquired 

 ^t the same time the property of converting vegetable blues 

 tb-a red ; even the last portions of water ai-sumcd a yellow 

 colour, a!thouo;li thev no longer showed the presence of any 

 acid/ The residuum., alter washing, acquired a still deept-r 

 coloUr, and when mixed with a little water reddened again 

 the paper of turnsole. 



When dissolved in alkalies it had a deep blood red co- 

 lour : acids, on the other hand, precipitated it in the form 

 of yellow fhikes. 



This matter is greasv and pitchy to the touch; it smells 

 like rancid fat, and ha-* a very acrid taste. 



The fusion and swelling which it undergoes when placed 

 over bunnng coals, the fumes of grease and the tcetid odour 

 which it ennts during this process, and the small portion 

 of charcoal which it Teavcs, render it akin to fatty mutters, 

 although in fact it appears to be acid. 



II. A more minute examination of this yellow substance 

 has shown it to possess the following pvoptriics : 



It neutralizes the alkalies so as to alter then- qualities al- 

 most entirely : its combinations with potash anil ammonia 

 froth like a solution of soap : they are not dccouqwsed by 

 the carbonic acid ; and ihey precipitate the solutions of 

 mercurv and lead in yellowish v. hite flakes. 



The vellow subitaiice decomposes the alkaline carbonates 

 with efiervescence even in the cold, and the solution of 

 acetate of potash with the assistance of a gentle heat. 



On the application of alcohol, to which the celebrated 

 authors of the memoir had next recour-e, the substance in 

 question is found to consist of a small quantity of greasy 

 matter which the alcohol takes up, and of an acid, to which 

 on account of its colour they have given the name ol the 

 ycLlfiw add. When deprived of the grease which alters its 

 properties, the vellow aed assumes a di:cper colour : it red- 

 dens in a greater degree turnsole paper; it no longer melts 

 in the same manner, and exhales not the odour ot burnt 

 grease, but foetid and anunoniacal vapours. 



The vellow acid dissolves in grease, and renders it at the 

 same time acrid and rancid. It combines with anunonia, 

 which It deprives of its odour; it yields, by distillation, all^ 

 the products of animal substances ; therefore consists ot 

 azote, hydrogen, carbon, and oxygen; and ought to be 

 ^'ankcd ainon<r the animal acids. 



\U. The yellow matter, composed of the yellow acid 

 X 4 and 



