HVDROXVLAMINE AND ITS SALTS. — ROSS. 101 



seemed to form independently throughout the li{|uid, and then 

 fall to the bottom like flakes of snow. The formation of 

 In'droxvlauiine pliosphate thus more resembles the crystallisa- 

 tion of a salt from its supersaturated solution, than the forma- 

 tion of a precipita e in a solution where two soluble salts react 

 so as to form an insoluble one. 



About 75 gn)s. of the salt were obtained. On account of its 

 being but slightly soluble in water, it can be purified with less 

 ditBculty than the other salts of hj^droxylamine. Like the 

 sulphate, however, it was found to decompose when a concen- 

 trated solution was heated to boiling. Considerable care had to 

 be taken to prevent this when pui-ifying the salt by recrystallis- 

 ing from water. On recrystallising eight times no trace of 

 sodium was found. 



Like many of the other salts of hydroxylamine, the phos- 

 phate forms supersaturated solutions of wonderful stability. 

 On account of this property, I had considerable difficulty in firsfc 

 preparing the salt. The two solutions were mixed while hot- 

 No phosphate crystallised out even when the solution was 

 allowed to stand over nigh', and stirred briskly. On cooling 

 down the solutions before mixing, as already mentioned, the salt 

 was finally obtained. 



Properties of Hydroxylamine Pltosphate. 



Hydroxylamine phosphate is much more soluble in hot than 

 in cold water. It is almost insoluble in alcohol. Its crystals 

 from water are coar.sely, or finely, granular according to 

 whether the solution from which they separate is very concen- 

 trated or less so. The crystals are not hygroscopic. When 

 lieated in a confined space they explode quite violently. Heated 

 in a vacuum, the salt decomposes into hydroxylamine, water and 

 pyrophosphoric acid : 



2 (N H3 O H)3 P O4 = 6 N H3 O + H, O + H4 Po O7. 



When heated in an open vessel the salt was found to decom- 

 po.se at about 148' into ammonia, water, phosphoric acid, normal 

 ammonium phosphate and nitrous oxide. The relative proportion 



Proc. & Trans. N. S. Inst. Sci., Vol. XI. Trans.— H. 



