318 PROCEEDINGS OF SECTION B. 



Crude hyponitrite of silver, prepared according to Divers' 

 method, invariably changes from a yellow to a green color. The 

 percentage of silver in four cases in which the crude product was 

 analysed varied from 77'4 to 84"8 (the theoretical percentage 

 being 78-2 per cent.), and it was found on treatment of the hypo- 

 nitrite with dilute sulphuric that this result was mainly due to the 

 presence of more or less finely divided silver. 



The only substances of a reducing character present in the 

 liquid from which the silver hyponitrite is precipitated are 

 potassium nitrite, acetic acid, and hydroxylamine acetate, and as 

 KNO2 will not reduce AgNO either in presence or absence of 

 acetic acid, the reduction must be due to the hydroxylamine 

 acetate. It thus appears that hydroxylamine acetate, though it 

 does not reduce (faintly acid) silver nitrate, possesses the property 

 of reducing AgNO to the metallic state. In accordance with this, 

 it was found that the filtrate from the precipitated hyponitrite 

 gave no trace of hydroxylamine, though the original alkaline 

 liquid readily gave the tests for it. This conclusion as to the 

 origin of the silver is to some extent confirmed by the recently 

 published papers of Wislicenus (Ber. Apr., 1893, p. 773) and 

 Paal (Ber., May, 1893, p. 1028). Wislicenus prepared hyponitrite 

 by the action of hydroxylamine sulphate on sodium nitrite ; Paal 

 by the action of hydroxylamine hydrochloride on silver nitrite. 

 Both found that the hyponitrite obtained contained metallic silver, 

 so that other hydroxylamine salts, as well as the acetate, reduce 

 AgNO. A specimen of AgNO was actually tried with acetic 

 acid and hydroxylamine acetate, and, in accordance with what has 

 been stated, was found to be reduced to metallic silver. 



In order to prevent loss of hyponitrite, therefore, by this 

 reduction it is advisable to treat the alkaline liquid with pre- 

 cipitated mercuric oxide. This decomposes the hydroxylamine. 

 The crude hyponitrite obtained in this case does not contain 

 metallic silver, and remains yellow in the dark under water. 



Preparation of the Sodmm Salt. — Although sodium hyponitrite 

 has never been satisfactorily obtained in the solid state, several 

 facts are known about its solution in water. Thus Divers shows 

 that this solution is alkaline to litmus, and that it gives precipitates 

 with certain salts of the heavy metals. He also mentions that 

 alkaline hyponitrites are decomposed by COo. It was found that 

 somewhat diluted solutions of sodium hyponitrite (prepared 

 according to the equation AgNO + NaCl = NaNO + AgCl), 

 or strong solutions which were slowly evaporated at the ordinary 

 temperature (in vacuo) gave no appreciable quantity of solid 

 hyponitrite. The residue contained, on the contrary, caustic soda, 

 so that the sodium salt had evidently decomposed in accordance 

 with the equation 2NaN0 + Ho O = 2NaH0 + N, O. As 

 caustic soda is produced in this hydi-olysis it was thought that 

 a strongly alkaline solution of sodium hyponitrite would be more 



