136 COMBUSTIBLE ACIDS. 



have nearly the same specific gravity. It is ob- 

 vious from this, that the specific gravity of an 

 acetic acid does not assist us in determining its 

 strength, or the true quantity of acid which it 

 contains.* 



SECT. V. 



OF THE ATOMIC WEIGHT OF SUCCINIC ACID. 



THIS acid, as it is at first obtained by the 

 distillation of amber, has a yellow colour, and 

 an empyreumatic smell, both of which are re- 

 moved by digesting it in nitric acid, which de- 

 composes the oily matter with which it was con- 

 taminated. When thus purified, its colour is 

 very white, and it crystallizes in four-sided 

 prisms. I do not find it to contain any water of 

 crystallization. The crystals consist entirely of 

 anhydrous acid. 



* In the two last editions of my System of Chemistry (Vol. II. p. 

 141.) I inserted a table, exhibiting the specific gravity of acetic acid of 

 various strength, deduced from the experiments of Mollerat. That table 

 is quite erroneous, as may be seen by comparing it with the one now 

 given. 



