6 AET. 2. — E. DIVERS AND T. HAU A. 



from the carbonate (using this in hydrated crystals, along with 

 only half its weight of water, and saturating with sulphur dioxide) 

 a fresh and pure solution of pyrosulphite as concentrated as 

 possible, pouring this solution upon the nitrite dissolved in its 

 weight of water, one mol. nitrite to every two mois, carbonate 

 taken, and shaking the flask in cold water for a short time to 

 moderate the rise of temperature, a solution is obtained which 

 will in an hour or two deposit a small quantity of sparkling 

 crystals of the nitrilosulphate, and give more when it is evaporated 

 over sulphuric aeid. The equation, 



NaNOo + 2Na 2 S 2 O g =N(S0 3 Na) 3 + Na 2 S0 3 , 

 represents the change but this would take many days to become 

 complete, long before which time the nitrilosulphate. would have 

 all decomposed. In the mixed solution only a few hours old, 

 some hydroximidosulphate, as well as nitrite, is still present. 



The only satisfactory method of preparing sodium nitrilosul- 

 phate is a slightly modified form ofthat employed by us to get the 

 imidosulphate (this Journal, 1894, 6, 65). In that process, which 

 is after all only a development of Fremy's method of preparing 

 the ammonium salt, the nitrilosulphate is prepared and at once 

 allowed to hydrolyse into imidosulphate, whereas in the present 

 ease its hydrolysis is to be prevented. There a moderately con- 

 centrated solution met the end in view, whilst here the greatest 

 possible concentration is wanted, because evaporation of the solu- 

 tion afterwards, though sometimes successful, is a very uncertain 

 operation, in consequence of the short existence which can be 

 assured to the nitrilosulphate. A solution therefore is prepared 

 of two mois, nitrite to three mois, carbonate, so concentrated that 

 the water is scarcely more than twice the weight of the anhydrous 

 carbonate (for example, 10 grams nitrite, 8.5 grams hot water, and 



