124 COMBUSTIBLE ACIDS. 



and the very same volume of carbonic acid gas 

 came over as when 9*375 grains of tartaric acid 

 crystals were decomposed in the same manner. 

 4'5 water indicate 4 atoms of that liquid ; but 

 the crystals contain 2 atoms of water ; conse- 

 quently, the other 2 atoms were formed by the 

 decomposition of the acid, and they indicate 2 

 atoms of hydrogen. The carbon, being the same 

 as in tartaric acid, amounts to 4 atoms, the 

 weight of which is 3. The weight necessary to 

 make up the whole 9*5 of citric acid decom- 

 posed must be oxygen. Thus it appears, from 

 the preceding analysis, that 9*5 of citric acid 

 crystals are composed of 



2 atoms water . 2-25 



2 atoms hydrogen . 0-25 



4< atoms carbon . 3-00 



4> atoms oxygen . 4-00 



9-5 



Thus, both the atomic weight and the constituents 

 of the acid are confirmed by this analysis. 



SECT. IV. 



OF THE ATOMIC WEIGHT OF ACETIC ACID. 



THE determination of the atomic weight of this 

 acid is attended with peculiar difficulties, be- 



