INTERACTION BETWEEN SULPHITES AND NITRITES. 307 



not freely form soluble pyrosulphites are difficult to work with. 

 Otherwise, the luitiire of the base seems to be a matter of in- 

 difference. Since the time of our early publications on the sub- 

 ject, we have extended our experiments to several other nitrites 

 than those of sodium, mercurosum, and silver, with the results 

 we now record. 



Ammonium salts. — Ammonium nitrite solution was prepared 

 by triturating silver nitrite with its equivalent of ammonium 

 chloride dissolved in about five times its weight of water, and 

 filtering off silver chloride over the pump. To this solution, 

 after it had been cooled in ice, w^as added a little less than its 

 equivalent of ammonia-water which had just before been con- 

 verted to sulphite by passing sulphur dioxide into it. jMore 

 sulphur dioxide was then passed into the mixture until it red- 

 dened lacmoid-paper. In this way the ammonium nitrite was 

 almost all sulphonated, without any evolution of gas having 

 occurred till just at the last, when slight nitrous fumes appeared. 

 Some of the solution was hydrolysed and tested then with copper 

 sulphate and potassium hydroxide ; it was thus shown to have 

 contained abundance of ammonium hydroximidosulphate. 

 Another portion of the solution not hydrolysed gave a large 

 precipitation of dipotassium hydroximidosulphate on addition of 

 potassium chloride. 



Barium salts. — Some barium hydroxide was converted into 

 sulphite by putting it in water and passing in sulphur dioxide ; 

 the barium sulphite was then, for the most part, brought into 

 solution by passing in more sulphur dioxide. The product was 

 added gradually to a solution of a little more than its equivalent 

 of barium nitrite, which had been purchased of excellent quality. 



