1825.] Three neio Salts of Soda. 445 



bottle, and allowed coniinon air to take its place. The loss of 

 weight sustained, owing to the escape of carbonic acid gas, was 

 8*47 grains. When dilute sulphuric acid was substituted for 

 nitric, the loss of weight was always less ; because a portion of 

 the carbonic acid remains in the liquid, and is extricated when 

 heat is applied. In two trials made in this way, the loss was 

 8*06 and 8*01 grains. From the experiment with the nitric acid, 

 which was twice made, it follows that 100 grains of the prismatic 

 carbonate of soda, if pure, would contain ]7*163 grains of car- 

 bonic acid. 



(4.) 50 grains of the salt were dissolved in nitric acid, and 

 the solution evaporated to dryness. The nitrate of soda 

 obtained weighed 35*59 grains, equivalent to 12*991 grains of 

 soda. 



50 grains were dissolved in sulphuric acid. The solution was 

 evaporated to dryness, and heated to redness with some carbo- 

 nate of ammonia to get rid of all excess of acid. The sulphate of 

 soda weighed 29*73 grains, equivalent to 13*213 grains soda. 



We cannot employ the quantity of sulphate of soda obtained 

 for determining the quantity of soda in the carbonate, because 

 the acid employed was the sulphuric acid of commerce, v.hichis 

 never quite free from lead. The soda in 50 grains of the carbo- 

 nate determined by the nitrate is 12*991 grains. Hence 100 grs. 

 of the salt contain 25*982 grains. If from this we subtract the 

 0*52 grain soda contained in the common salt present m the salt, 

 ,there will remain 25*462 grains of soda as the constituent of 98*7 

 grains of pure carbonate. Hence 100 grains contain 25*797 grs. 



Thus the constituents of the salt are as follows : 



Carbonic acid 17*163 or 2-661 



Soda 25-797 4*0 



Water 56*920 8*824 



99*880 

 Loss 0*12 



100*000 



The second column gives the atomic equivalents for the con- 

 stituents. If we consider the loss as carbonic acid, which it 

 was most likely to be, then the equivalent for the carbonic acid 

 is 2*68, which is about ^^-^^-th less than the weight of an atom. 

 The soda was originally in the state of sulphate. It was con- 

 verted into sulphuret by heating it with combustible matter 

 (common pit coal). The sulphuret thus formed was dissolved in 

 water, evaporated to dryness, mixed with saw-dust, and exposed 

 to a heat strong enough to consume the saw-dust. By this pro- 

 cess the sulphur is disengaged, and carbonic acid takes its place. 

 Mr. Tennant's soda usually contains a small portion of sulphate 



