22 REDUCTION OF ALKALI NITRITE BY AN 



more is necessary than to work with a concentrated sokition of 

 the nitrite (1 sodium nitrite to 3 or 3^ water), and add the 

 amalgam in some excess. All else to attend to is that the 

 temperature should not be allowed to rise above 100°, at first, as 

 the yield is a little lowered otherwise. To get as much hydroxyl- 

 amine as possible, the solution of nitrite must be dilute (say 

 1 in 50) and be kept cold, during the addition of the amalgam. 

 To preserve the hydroxylamine from reduction into ammonia, 

 the solution should throughout be kept well agitated over the 

 amalgam and be poured off from it as soon as nearly all nitrite 

 has been reduced. Much more time is needed to reduce a dilute 

 solution than a concentrated one. The best conditions for pro- 

 ducing hydroxylamine, do not allow of much more than half 

 the best yield of hyponitrite being obtained at the same time. 



To get much nitrous oxide the temperature of the solution 

 must be kept as low as possible, while to get much nitrogeii the 

 temperature must be kept high. The strength of the solution 

 of nitrite is here without effect, provided that the temperature is 

 properly regulated by external heating or cooling, as may be 

 called for. The reduction of a very dilute solution of sodium 

 nitrite kept very cold, is attended with very little effervescence, 

 because the quantity of nitrogen produced is very small and 

 the nitrous oxide remains dissolved, though ready to escape 

 when the solution is warmed. De Wilde has determined the 

 proportions of gases to each other, but only when the nitrite 

 (or nitrate) was in excess of the sodium. That, however, is 

 sufficient, since qualitative examination of the gases has shown 

 me that variations in the proportions of salt and metal are 

 without sensible influence upon the composition of the gases, and 

 also that this remains apparently unchanged during the progress 



