380 Proceedings of Philosophical Societies. [May, 



which, falling into the solution, take away a portion of the 

 oxygen that is essential to its existence. 



Cobalt and nickel are two semimetals which it is very difficult 

 to obtain in a state of purity, and still more difficult to separate 

 entirely from one another ; nevertheless this purification is neces- 

 saiy for an exact determination of their respective properties. 

 M. Laugier having tried the newest methods that have been 

 pubhshed as proper to obtain this object, has found in nickel 

 unequivocal traces of cobalt. In order to get rid of them, he 

 dissolved the mixed metal in ammonia, and precipitated it by 

 oxalic acid ; he then redissolved the oxalate of nickel and 

 cobalt obtained by this operation in concentrated ammonia, and 

 exposed the solution to the air. As the ammonia exhaled, 

 oxalate of nickel mixed with ammonia was deposited. The 

 nickel was entirely separated from the Hquid by repeated crys- 

 tallizations ; so that there remained only a combination of 

 oxalate of cobalt and ammonia, which was easily reduced. The 

 small quantity of cobalt that remained in the nickel that was 

 precipitated was separated by several successive solutions in 

 ammonia; so that one and the same operation yielded both 

 metals iu a state of purity. 



Sugar of milk, treated with nitric acid, yields an acid, origi- 

 nally discovered by Scheele, and which has been since called 

 the mucic acid, because it is also produced by the action of 

 nitric acid upon gums and mucilages. When this acid is 

 exposed to heat, a brown saUne matter is subhmed, of a strong 

 smell, soluble in water and alcohol, and burning with a flame 

 upop lighted charcoal. Trommsdorf, who particularly examined 

 this sublimed substance. Conceived he had found in it succinic 

 acid, pyrotartaric and acetic acids, and several other substances ; 

 but M. Houton-Labillardiere perceiving, upon the reading of 

 Trommsdorf's essay, that he attributed to the succinic acid very 

 different characters from those that this acid really possesses, 

 thought proper to resume the research. 



He has read a memoir to the Academy, in which he proves 

 that this pretended succinic acid is a new acid, to which he 

 gives the name of pyromucic acid. When it is cleared from 

 the oil and acetic acid with which it is mixed, it easily crystal- 

 lizes, and is white, scentless, of a strong acid taste ; it melts at 

 130 centigrade degrees (266° Fahr.) is volatilized at a little above 

 that temperature, does not attract moisture, dissolves much more 

 abundantly in boiling water than in cold ; and upon its being 

 resolved into its constituent parts, there were obtained from it 

 about nine volumes of the vapour of carbon, three of hydrogen, and 

 two of oxygen. M. Houton-Labillardiere carefully describes the 

 combinations of this acid with different salifiable bases, and all 

 the appearances that he relates support the assertion of thi^ 

 young and skilful chemist. 



