ECONOMIC PREPARATION OF HYDROXYLAMINE SULPHATE. ^«)3 



The crude hydroxylamine sulphate weighs about !) parts for every 

 10 parts of sodium nitrite taken. It needs to be recrystallised, but 

 the mother-liquors can be closely worked up. On the other hand, the 

 sodium sulphate recrystallised, or even washed with ice-water will 

 give up 1 part more of hydroxylamine sulphate ; so that sodium 

 nitrite will yield, on the small scale, nearly its own weight of pure 

 hydroxylamine sulphate. No doubt, on the large scale, the theoretical 

 yield of 118*84 per cent, could be more nearly approached. 



Potassium nitrite is not well fitted lor the preparation of 

 hydroxylamine, because of the difficulty experienced in closely 

 separating its sulphate from that of potassium. After several 

 recrystallisations, the hydroxylamine salt contains 1*8 per cent, of 

 potassium sulphate. The addition of aluminium sulphate is not an 

 improvement, for then the hydroxylamine sulphate, separated as far 

 ;is practicable from the potassium alum, leaves behind on ignition as 

 much as 5*7 per cent, residue. 



