Intelligence mid Miscellaneous Articles. 1 69 



which is not increased when the oleic acid employed contains other 

 fixed fatty acids : wax yields no sebacic acid by distillation, there- 

 fore it contains no oleic acid, nor does spermaceti. M. Thenard 

 has indeed indicated the formation of sebacic acid during the distil- 

 lation of wax, as a means of determining whether it is adulterated 

 with fat. 



As sebacic acid is but very sparingly soluble in cold water, it is 

 easily recognised, both by its appearance and its reaction with the 

 salts of lead, mercury, and silver ; and as it is sufficient to distil less 

 than an ounce of any fatty body, the sebacic acid from the product 

 of which is easily se])arated by boiling water, it must be admitted 

 that sebacic acid is the best reagent for detecting the presence of 

 oleic acid in a fatty matter. This fact is especially important in the 

 preparation of margarin and stearin, the only method which has been 

 hitherto employed consisting in the saponification of the fatty matter, 

 and ascertaining the fusing point of the fatty acid set free. 



The best process which can be employed for the preparation of 

 sebacic acid is that of distilling the rough oleic acid produced in the 

 manufacture of stearin candles. — An?i. de Chim. etdePhys.,Sept. 1841. 



EUCHROIC ACID. 



M. Woehler finds, that when melUtate of ammonia is heated to 

 302" Fahr. much ammonia is evolved and water evaporated, and the 

 salt is converted into two new azotized bodies, one of which is an 

 acid and remains combined with ammonia, in the form of an am- 

 moniacal salt, while the other is quite insoluble in water. The dis- 

 engagement of ammonia commences at 212°, and when the tempera- 

 ture is raised to above 320° Fahr., secondary products are formed 

 which interfere with the results. 



When the decomposition is complete, the salt is changed into a 

 pale yelloAV powder which is separated by water into two substances, 

 namely, an ammoniacal salt which is dissolved, and a white sub- 

 stance which remains undissolved ; the former is euchroate of am- 

 monia, and the laXter par amide. 



If the decomposition has not been complete, the euchroate of 

 ammonia contains excess of acid, or rather supereuchroate of am- 

 monia ; and if the heat be too great, the yellow bitter substance al- 

 ready mentioned is produced. The ammoniacal salt with excess of 

 acid is deposited in imperfectly crystalline scales, which are but 

 sparingly soluble in cold water, and have a strongly acid reaction. 



To obtain the acid from the ammoniacal salt, it is to be dissolved 

 in the smallest possible quantity of boiling water, and nitric or hy- 

 drochloric acid is to be added to the hot solution. As soon as the 

 temperature is lowered a few degrees, the euchroic acid begins to 

 separate in the form of a white crystalline powder, and after cooling 

 but little of it remains in solution. It is to be purified by repeated 

 solution in hot water and crystallization ; by long and well managed 

 cooling, small, but very distinct crystals are obtained. 



This acid crystaUizes in very flat four-sided prisms, which are 



