42 Upon the Comlination of the fixed Oils 



really more oesonomical to extract barytes from the nitrate 

 by means of fire than to follow M. Darcet's process ; for, 

 even supposing that the quantity of barytes was equal in botJi 

 cases, what I have demonstrated could not exist — the price 

 of the potash I was obliged to employ would have cost me 

 almost double the expense. As to the purity of the article, as 

 we are obliged to manage the washings carefully, I do not 

 see that the process of M. Darcet merits the preference in 

 this respect j for it is very probable that the barytes thus 

 obtained should retain a little of the salt contained in the 

 mother water ; and, on the contrary, that extracted from 

 the nitrate is extremely pure, if before decomposing it we 

 take the precaution of calcining it slightly and redissolve it, 

 in order to separate a portion of the iron proceeding from 

 the sulphate employed. 



X. Olservations upon the Combination of the fixed Oils 

 with the Oxides of Lead and the Alkalis, By M. Fremy, 

 Apothecary at Versailles*, 



fccHEELE was the first who observed that the water which 

 serves as an intermedium, when we treat the fat oils or the 

 fats by litharge, retains in solution a substance to which he 

 has giv^ the name ef sweet principle of oils ^ because it has, 

 in fact, a very decided saccharine taste. But, according to. 

 the observation of this illustrious chemist, this water hold- 

 ing also in solution a certain quantity of oxide of lead, may 

 we not think that the taste, which suggested to him the 

 name of the sweet principle, proceeds from the property pos- 

 sessed by this metal of communicating a saccharine taste to 

 most of its combinations ? Where experience has demon* 

 Strated the contrary, would it not be interesting to inquiry 

 how this principle came to be formed ? What are its proper- 

 ties ? In what state the oil exists after having abandoned thq 

 principles which should have given rise to it? If this sub- 

 traction it) absolutely indispensable for forming the combi- 



• From Annales de Chimie, torn. Ixii. p. 25. 



nation 



