266 M. Labillaidiere on a new Acid [Oct. 



acid, because he considered it peculiar to sugar of milk. The 

 same acid was met with afterwards while treating gums with 

 nitric acid, and received the name of mucous acid, finally, the 

 name of muck acid was given to it to render it conformable to 

 the names of the other acids. 



Scheele, while examining the properties of this acid, subjected 

 it to the action of heat in a retort, and observed that during its 

 decomposition there sublimed into the upper part of the retort a 

 brown salt, which had a smell similar to that of a mixture of 

 benzoin and amber, which was soluble in water and alcohol, and 

 burned with flame upon red-hot coals ; and that the liquid which 

 passed at the same time during the distillation contained the 

 same matter in solution. 



Trommsdorf* resumed the experiments of Scheele on this 

 subject, with a view to examine with care the nature of this crys- 

 talline substance, and observed that during the calcination of 

 mucic acid, there were- formed succinic, pyrotartaric, acetic 

 acids, an empyreumatic oil, water, and carbonic acid, and carbu- 

 retted hydrogen gases. 



Having read the result of the experiments by which Tromms- 

 dorf undertook to prove the identity of this crystalline matter 

 with succinic acid, 1 observed that in the comparison which he 

 drew between the two bodies, he ascribed properties to succinic 

 acid very different from those which it really possesses ; such as 

 the solubility of succinate of copper and of lead : and that the 

 experiments from which he infers the presence of pyrotartaric 

 acid are not more conclusive. These facts induced me to repeat 

 the experiments of these two chemists, and I satisfied myself 

 that during the calcination of mucic acid neither succinic nor 

 pyrotartaric acid was formed; but a peculiar acid to which I 

 give the name of pyromucic acid, from the analogy of its forma- 

 tion with that of pyrotartaric acid. 



Mucic acid calcined in a retort gives for products a very acid 

 brown liquid, accompanied with some crystals, a small part of 

 which remain attached to the upper part of the retort : it gives 

 also carbonic acid and carburetted hydrogen gases, while a light 

 charcoal remains in the retort. The acid formed in this case is 

 almost completely dissolved in the liquid, and mixed with a little 

 acetic acid and empyreumatic oil, which prevents it from crys- 

 tallizing. To separate these two matters, the crystals are added 

 to the liquid, and it is mixed with twice or thrice its volume of 

 water, which precipitates a part of the empyreumatic oil, and 

 after having filtered the liquid, it is evaporated till it deposits 

 crystals. The greatest part of the acetic acid separates during 

 the evaporation, and the new acid then crystallizes with facility. 

 After separating the crystals, the mother-water is evaporated 

 again to extract the rest of the acid. In this state, it is m small 

 yellow crystals, which are very difficult to purify by repeated 



* Ann. de Chim. Ixxi, 79. 



