Chemistry and Physics. 317 



of the experiments the value obtained would be 2*002466 ± 

 0-000003, the impurity making no difference whether assumed to 

 be all in the hydrogen or equally distributed between the two 

 gases. The most probable value is 2*00245 ; which combined 

 with Rayleigh's value 15-882 for the ratio of the densities of the 

 gases, gives 15-862 for the atomic mass of oxygen, hydrogen be- 

 ing 1 ; or 1-0078 for the atomic mass of hydrogen, oxygen being 

 taken as 16. — Proc. Roy. Soc, liii, 130; J. Chem. Soc, lxiv, ii, 

 575, November, 1893. G. F. B. 



5. On the Production of Hyponitrous acid. — The results of 

 the reduction of sodium nitrite in alkaline solution have been 

 studied by Thum. He finds that the first product of this reac- 

 tion is the sodium derivative of a dihydroxylamine, two molecules 

 of which subsequently condense to form sodium hyponitrite : 



Na,+ (H o 0) a + NaN0„ = NaN(OH) 2 +(Na(OH))„ 

 and (NaN(OH) a ) s = ]Sra 9 TSr 2 O a + (H 9 0) a 



This second reaction seems to be favored by an excess of alkali, 

 for if this be neutralized by a current of carbon dioxide, no hypo- 

 nitrite is formed. The nitrogen which is set free during the 

 reaction is not due to the reduction of hydroxylamine, as usually 

 supposed, for this substance is scarcely attacked by sodium amal- 

 gam ; it results probably from a reaction between the dihydroxyla- 

 mine and hydroxylamine NH„OH + NH(OH) a = N 2 + (H 9 0) s . 

 For the preparation of hyponitrites, ferrous hydroxide has no ad- 

 vantage over sodium amalgam. Hyponitrous acid may also be 

 formed by the action of nitrous acid on hydroxylamine. When 

 equivalent solutions of hydroxylamine hydrochloride or sulphate 

 and of sodium nitrite are mixed, allowed to stand until the violent 

 evolution of nitrous oxide has ceased and then treated with silver 

 nitrate, silver hyponitrite is formed in amount equal to about 2 

 per cent of the theoretical yield. In alkaline solution, however, 

 no hyponitrite is formed. The acid itself may be isolated by 

 acting on the silver salt with the theoretical amount of hydrogen 

 chloride. A colorless and strongly acid solution results which is 

 stable towards dilute acids and alkalies even on boiling. On 

 titration with potassium hydroxide, in presence of phenophthalein 

 or litmus, the solution remains acid until the acid salt is formed 

 and then becomes alkaline. The acid does not affect methyl- 

 orange and does not expel carbon dioxide from the alkali-carbo- 

 nates. In acid solution- it is converted by potassium permanga- 

 nate quantitatively into nitric acid ; while in alkaline solution 

 nitrous acid is formed. Pure solutions of hyponitrous acid do not 

 decolorize solutions of iodine and they prevent the formation of 

 iodide of starch. Moreover, they do not liberate iodine from acid 

 solutions of potassium iodide. The acid, in both acid and alkaline 

 solutions, is very stable towards reducing agents. The acid 

 hyponitrites of the alkalies give precipitates with many metallic 

 salts. — Monatsb., xiv, 294 ; J. Chem. Soc, lxvi, ii, 13, January, 

 1894. G. F. B. 



