THE REDUCTION OF NITROSOSULPHATES. 279 



water to 1 part salt. To the water has been added, at starting, 1 per 

 cent, of its weight of sodium hydroxide, as a precaution. When much 

 less than 10 parts of alkaline water are taken, some of the salt remains 

 undissolved during the earlier stages. From this cause, less than 3 

 parts water are insufficient. The amalgam we used was one of about 

 2\ per cent, sodium. The reduction goes on rapidly at the common 

 temperature and is attended with much heating. If the nitrososul- 

 phate solution is cooled below 0°, sodium amalgam acts upon it only 

 when it first comes in contact with it ; perhaps, it would not even 

 then, if it itself were first cooled down. At this low temperature, action 

 is arrested for any period ; but soon after the vessel is removed from its 

 bath, action sets up and, once started, is not easily checked by returning 

 the vessel to the bath, the solution being kept warm by its interaction 

 with the sodium. A moderate rise of temperature, up to 40°, for instance, 

 does not seem to lessen the production of either hydrazine or hyponitrite, 

 or to affect their preservation. The sodium requisite to reduce the 

 nitrososulphate is, as nearly as could be estimated, 3Na \ K 2 N 2 S0 6 ; but 

 to destroy all the hydrazine much more is required (we used 2 Na 

 additional for this purpose). After the main change is complete, the 

 interaction between amalgam and solution is very slow ; the solution 

 remains cold, and hydrogen makes its appearance, along with much 

 ammonia. The contact of amalgam with the solution has been main- 

 tained in our experiments for 24 hours, or for 2 days ; but, with 

 continuous shaking during the second stage, much less time would 

 have sufficed. We used a stoppered vessel, the loose stopper actinc 

 effectively as a valve in keeping air out. 



Hydroxi/lamine a product of the reduction of a nitrite by sodium 

 amalgam. — The testing for a small quantity of hydroxylamine, alone 

 or in presence of hydrazine, possessing some novelty, it is well to de- 

 scribe the positive result in the case of sodium nitrite, before the negative 



