118 COMBUSTIBLE ACIDS. 



double that procured from 9 grains of crystal- 

 lized oxalic acid. 



Now, the 9*375 grains analyzed contained 

 1 -125 grain of water. The residual Q'%5 grains 

 of water indicate O25 of hydrogen. The quan- 

 tity of carbonic acid evolved showed that the 

 carbon in 9*375 of tartaric acid crystals is just 

 double that in 9 grains of oxalic acid crystals. 

 But we have seen in the last section, that the 

 carbon in 9 grains of the crystals of the latter 

 acid is 1-5 grain: consequently, 9*375 grains of 

 crystallized tartaric acid contain 3 grains of car- 

 bon. The 5 grains wanting to make up the 

 weight must be oxygen. Thus it appears, that 

 the constituents of 9*375 grains of crystallized 

 tartaric acid are as follows : 



1 atom water = 1-125 



2 atoms hydrogen = 0-25 



4 atoms carbon = 3 



5 atoms oxygen = 5 



9'375 



Some years ago, Dr. Prout gave me the result 

 of a set of experiments which he had made, to 

 determine the composition of tartaric acid in 

 crystals. The table which he gave me was as 

 follows : 



3 atoms hydrogen 0-375 



4 atoms carbon 3 

 6 atoms oxygen 6' 



9-375 



