S0DIU3I OK POTASSIUM : EDWARD DIVEES. 47 



solve up all lumps and should again be stirred when solidifying, 

 in order to disturb crystallisation as much as possible. The 

 specific gravity of paraffin wax is about the same as that of 

 potassium, but paraffin expands so very greatly in melting that 

 the potassium readily sinks in it when it is in the liquid state. 

 Muhlhaeuser, many years ago, melted sodium under petroleum 

 and then added the mercury to it, and, in recent years, Nef has 

 recommended the use of toluene, which l3oils freely l)y the heat 

 of the union of the metals. But toluene could hardly be used 

 ill making potassium amalgam, because of its specific gravity. 



A highly concentrated solution of potassium hyponitrite 

 and liydroxide having been prepared, the hyponitrite can be 

 precipitated l)y absolute alcohol, but only very incompletely 

 and some of what is precipitated is afterwards dissolved away 

 in washing it with more alcohol. The preparation of this salt 

 is therefore less satisfactory than that of the sodium salt. 



Another way of making potassium hyponitrite is to decom- 

 pose silver hyponitrite with exactly the right quantity of solu- 

 tion of potassium iodide. By rapid evaporation under reduced 

 pressure the solution can be concentrated, as preparation for 

 treating it with absokite alcohol, tliough with partial decom- 

 position of the salt, and can even be dried up, so as to yield 

 the impure solid salt. The cold of evaporation in a vacuum has 

 sometimes caused the separation from the concentrated solution 

 of hydrated crystals which, liowever, melt wlien placed on filter 

 paper ; otherwise, the salt is obtained anhydrous in minute 

 prismatic crystals. The salt decomposes more rapidly than the 

 sodium salt, but is stable when quite dry. It is soluble in 90 

 per cent, spirit, and slightly even in absolute alcohol. Its 

 aqueous or alcoholic solution yields silver hyponitrite with sil- 



