98 CONTRIBUTION TO THE STUDY OF 



I had a large amou.j-f^^^f the impure salt to start witli.aiid made 

 many crystallisations, yet I failed to obtain crystals sufficiently 

 free from sodium to be used in determining the electrical con- 

 ductivity of the salt. The purity of the salt was determined 

 roughly by heating a few crystals on a crucible cover. The 

 amount of sodium sulphate left behind after the hydroxylamine 

 sulphate had been volatilised, gave a rough idea of the amount 

 of sodium present. 



The hydroxylamine sulphate obtained in this way, however, 

 was sufficiently pure for the preparation of the other salts of 

 hydroxylamine, and finally hydroxylamine itself. By treating 

 a dilute standard solution of the latter with the required amount 

 of a dilute standard solution of sulphuric acid, a solution of 

 Iwdroxylamine sulphate was obtained. This solution was evap- 

 orated to dryness on the water bath, first in an open vessel and 

 then at reduced pressure. The salt thus obtained was purified 

 by digesting with alcohol in an upright condenser. As both 

 hydroxylamine and sulphuric acid are readily soluble in alcohol, 

 while hydroxylamine sulphate is not, the latter was thus 

 obtained in perfectly pure condition by decanting ofi' the alco- 

 hol, and repeating the process a couple of times. 



Properties of Hydroxylamine Sidijltate. 



Hydroxylamine sulphate was obtained on crystallising from 

 water in the form of irregular transparent 'crystals, which were 

 found to be slightly hygroscopic. The melting point of the 

 crystals was found to be about 163^ This is somewhat difficult 

 to determine exactly, as they undergo decomposition at the same 

 temperature According to Lossen they melt at 170°; while 

 Preibisch reports the melting point as being only 140". 



On heating above the melting point, the salt was found to 

 break up into water, sulphur dioxide, nitrous oxide and ammoni- 

 um sulphate — the greater part of the latter remaining behind 

 after the other products have passed ofi". 



