HYPONITRITES. 319 



stable. Siich a solution was prepared by reducing a strong 

 solution of Xa NOn with sodium amalgam, and was evapoi-ated in 

 a vacuum over sulphuric acid. Although the evaporation took 

 several weeks, the residue contained abundant hyponitrite of soda 

 — a more soluble salt apparently than caustic soda. Some of the 

 crystals Avere pressed between sheets of blotting-paper, redissolved 

 in water, neutralised, and used to precipitate solutions of the heavy 

 metals. Another portion of the crystals was treated with strong 

 alcohol, and it was found that the hyponitrite remained undissolved, 

 and could thus be completely separated from caustic soda. Dry 

 sodium hyponitrite, freed from cau>*tic soda in this way, was placed 

 in an ordinary desiccator, and kept for weeks without being 

 noticeably altered. The preparation of sodium hyponitrite by the 

 above method is not a satisfactory one, however, as the evaporation 

 of the alkaline liquid is very slow, and the product is impure. An 

 attempt was therefore made to isolate the salt by precipitating a 

 strong solution (from AgNO and NaCl) with alcohol. Crystals 

 separated out immediately and settled on the sides of the flask in 

 groups of plates. I satisfied myself that these were crystals of 

 sodium hyponitrite, and converted them, after carefully drying in 

 vacuo over sulphuric acid, into sodium sulphate in order to determine 

 the percentage of sodium. Found 43-0 per cent, of Na. Calculated 

 for the formula Na NO, 43-4 per cent. The salt, when separated 

 by means of alcohol and dried in this way, has therefore the com- 

 position Na NO. 



Before lea-sing the subject of sodium hyponitrite it may be well 

 to lay stress upon its decomposition by water. This decom- 

 position takes place in time at the ordinary temjierature, and is 

 much more rapid at higher temperatures. It gives an easy 

 explanation of the small yield obtained by most of the known 

 methods of preparation, and is in accord with the statement of 

 Divers, that the decomposition of the oxyamido-sulphonates is by 

 far the most productive method of preparation, since in this method 

 the strongest potash obtainable is used to eff'ect the decomposition 

 of the oxyamido-sulphonate into hyponitrite and sulphite. It indi- 

 cates, moreover, that success in obtaining large quantities of hypo- 

 nitrite will depend on the use of some liquid which, like alcohol, 

 will remove the hyponitrite out of the sphere of action of water. 

 Hyponitrous acid and all the alkaline and alkaline-earth hyjioni- 

 trites show more or less tendency to decomposition in presence of 

 water. 



Ammonium Hyponitrite. — Our knowledge of this is almost con- 

 fined to the original statement of Divers, that it exists in solution, 

 but is unstable. Ammonium chloride and silver hyponitrite, or 

 barium hyponitrite and ammonium sulphate, readily react, and a 

 solution containing hyponitrite is thus obtained, but it leaves no 

 residue on evaporation under the pump, the smell of ammonia 

 observed indicating the decomposition of the salt with separation 



