SODIUM Oll POTASSIüJr : EDWARD DIVERS. 37 



As witli tlie strength of the amalgam, so it is with the 

 temperature to be maintained during the reduction ; it does 

 not much matter if only the solution of nitrite is concentrated, 

 and then no better results can be got than by following my 

 original direction to keep the flask in a stream of cold Avater 

 during the reduction. The temperature may, in fact, rise nearly 

 to 100° without harm being noticeable, and even by letting the 

 solution boil freely l)y its own heating up, the temperature 

 then rising to 125-8°, the yield is only reduced by nearly a 

 third. But it is preferable to apply cold externally, particu- 

 larly in warm weather, by means of a brine-and-ice bath, 

 because then the amalgam can be added much faster, without 

 leading to great evaporation of water. The temperature of the 

 solution during the reduction then ranges, witli convenient rate 

 of working, from 5° to 25°. The time taken to add 23 grams 

 of sodium is not more than ten minutes. 



From a quarter to a half gram molecule of sodium nitrite 

 is a convenient quantity to work upon, and its solution is best 

 contained in a 3Ô0 to 4'jOcc. pyriform, wide-mouthed Hask, 

 lying very obliquely in the cooling bath during the addition 

 of the amalgam by aid of a spatula. The last fourth of the 

 amalgam may be put into the flask as rapidly as it can be, 

 and the flask may then be removed from the bath. It is kept 

 actively rotated for ten or fifteen minutes, during which the 

 temperature of its contents will rise to about 40° and then fall. 

 The two liquids are next poured into a stoppered bottle (best, 

 narrow-mouthed) sufficiently capacious to l)e aljout half filled by 

 them. The thick aqueous solution adhering to the flask may 

 be washed out into the bottle, but the w^ater should be limited 

 to 2 or occ. when the purpose is to obtain afterwards the solid 



