454 COMPOUND SALTS, CONTAINING 



Now, 



4 atoms phosphoric acid 14 



1 atom carbonic acid = 2-75 



5 atoms soda . . = 20 



55 atoms water . = 61-875 



Hence, I am disposed to consider the salt as a 

 compound of 



4 atoms phosphate of soda 30 

 1 atom carbonate of soda 6*75 



55 atoms water . . 61-875 



98-625 



If this be really a compound of phosphate and 

 carbonate of soda, the union is very slight ; for 

 I found that by repeated solutions, and crystal- 

 lizations, I could separate from it phosphate of 

 soda in the usual rhomboidal form. What leads 

 to the notion that it is a compound salt, is the 

 form of the crystals a six-sided prism apparent- 

 ly regular, which could not be derived from the 

 primary form of phosphate of soda. Nor is the 

 water of crystallization what it would be if the 

 salt were a mere mixture of 4 atoms of phosphate 

 of soda, and 1 atom of carbonate of soda ; for 

 phosphate of soda containing 12 atoms, and car- 

 bonate of soda 10 atoms, the water of crystal- 

 lization should have amounted to 58 atoms, in- 

 stead of 55 the quantity found, unless there 

 was an error in the analysis. I do not well see, 



