ii2 SCIENCE PROGRESS 



behaviour of sodium hydride when saturated with ammonia, 

 he inclined to the opinion that it was an ammoniacal mercury 

 hydride. 



Ruff(u) attempted to prepare ammonium by the electrolysis 

 of potassium iodide in liquid ammonia but without success. 

 At the negative pole he obtained a solution of potassium- 

 ammonium as a metallic-looking liquid, as described by Joannis ; 

 on coming into contact with the ammonium iodide formed at 

 the anode, this was decomposed but the ammonium which it 

 was thus hoped to obtain was dissociated into hydrogen and 

 ammonia. To prevent this dissociation, the experiment was 

 performed under a pressure of sixty atmospheres but without 

 success. This indicates that ammonium cannot exist at — 95 C. 

 at a pressure of sixty atmospheres. 



Now it has been already pointed out that the substituted 

 alkali ammoniums are very easily dissociated ; and by analogy 

 with these, Ruff regards ordinary ammonium as hydrogen 

 ammonium and draws the conclusion that the limits of the 

 existence of ammonium probably are to be found in the neigh- 

 bourhood of the critical point of hydrogen. As the critical 

 temperature of hydrogen is as low as — 238°C, no suitable 

 solvent is known which could be used for this purpose ; hence 

 the truth of this view cannot be tested. 



Ammonium in which the hydrogen atoms have been sub- 

 stituted by organic radicles might be expected to be more 

 stable; therefore Palmaer (12) attempted to prepare tetraethyl- 

 ammonium by electrolysing tetra-ethylammonium hydroxide 

 dissolved in liquid ammonia. The hydroxide, which contained 

 about 2*5 per cent, of chloride, was electrolysed between platinum 

 electrodes, when blue striations were seen at the kathode ; these 

 were thought to be tetra-ethylammonium. 



Ammono-Bases, Acids and Salts 



The blue solution formed when sodium or potassium is 

 dissolved in ammonia slowly changes on standing into a 

 solution of sodium or potassium amide, the interaction taking 

 place more swiftly in presence of a catalyst such as ferric 

 oxide or platinum black : 2K + 2NH 3 = 2K . NH 2 + H 2 . The 

 potassium amide remains dissolved in the ammonia ; the 

 solution exhibits basic properties quite analogous to those of 

 an aqueous solution of potassium hydroxide. Anhydrous liquid 



