ÖÖDIUM UK l'ÜTASSIÜM : EDWARD UlVEliS. 35 



Preparation of sodium hyponitrite solution by reduction 

 of sodium nitrite by sodium amalgam. 



Sodium nitrite can be converted by sodium amalgam in 

 the easiest and (juickest imaginable way into fully one-sixth of 

 its equivalent of sodium hyponitrite, existing in solution and 

 pure but for the presence of much sodium hydroxide. From this 

 solution the sodium salt itself, as well as silver hyponitrite, can 

 be at once prepared nearly pure and with hardly any loss, the 

 presence of nuich sodium hydroxide being no hindrance. The 

 solution becomes also at once fit for preparing lead, copper, 

 mercury, and some other salts, merely by cautious neutralisation 

 of the hydroxide, which is known to be comj^lete when a little 

 of the solution just ceases to give black oxide when mixed with 

 a drop of dilute solution of mercurous nitrate. Others Avho 

 have tried this method, and particularly the latest Avorkers, 

 Hantzscli and Kaufmann, have got no such favourable results, 

 these chemists having got only from a third to less than half 

 as much silver hyponitrite as is to he obtained under the best 

 way of working, while D. H. Jackson got with difliculty the 

 sodium salt in quantity too small for investigation. 



Pure sodium nitrite is necessary, but that can be prepared 

 very simply, as described in a note contained in this volume, 

 p. 1Ö. In order to get the most hyponitrite and the least 

 hydroxylamine, the nitrite must be in concentrated solution ; 

 three times its weight seems to be the best quantity of water 

 to dissolve it in when evaporation of the water during the 

 reaction is kept down by operating in the way to be just 

 now described, or three-and-a-half times when marked eva- 

 poration is caused by allowing greater rise of temperature. 



