72 Scientific Intelligence. 



SCIENTIFIC INTELLIGENCE. 



I. Chemistry and Physics. 



1. On the Production of Silver hyponitrite from Uydroxyl- 

 amine. — The fact that on mixing at ordinary temperatures hydrox- 

 ylamine sulphate and sodium nitrite in concentrated aqueous 

 solution, mutual decomposition takes place with the evolution of 

 nitrogen monoxide, was first pointed out by V. Meyer. If the 

 solutions be dilute, the same reaction takes place on heating ; 

 but if the temperature be not raised the. decomposition proceeds 

 slowly and if silver nitrate be added to this solution a yellow 

 precipitate of silver hyponitrite is thrown down which may be 

 purified by dissolving it in cold dilute nitric acid and reprecipi- 

 tating with ammonia. W. Wislicenus has shown that this reac- 

 tion may readily be used as a lecture experiment. For this pur- 

 pose two or three grams of hydroxylamine sulphate and the 

 equivalent quantity of sodium nitrite are dissolved separately in 

 about 100 cc of water, the solutions are mixed, and a portion is 

 tested with silver nitrate. A white precipitate of mixed silver 

 sulphate and silver nitrite results. The rest of the solution is 

 heated rapidly to 50° on the water bath for a few moments, the 

 evolved gas being shown to be nitrogen monoxide by means of a 

 glowing splinter. On adding now silver nitrate to the solution, 

 a yellow precipitate of silver hyponitrite Ag 2 N a 2 will be thrown 

 down. Experiment will determine the time of heating necessary 

 to secure the best results. — Ber. JBerl. Chem. Ges., xxvi, 771, 

 April, 1893. g. f. b. 



2. On the Electrolysis of Alkali /Salts. — From recent experi- 

 ments by Arehentds, it appears that upon electrolyzing an aque- 

 ous solution of an alkali salt, using mercury as the cathode, a 

 considerable time elapses after the passage of the current before 

 hydrogen makes its appearance. From this fact it would appear 

 that hydrogen is not a primary result of the electrolysis, but is 

 due to the secondary action of the water of the solution upon the 

 alkali amalgam pi*oduced primarily by the discharge of the posi- 

 tive ion; i. e. the alkali metal. The time required before the first 

 bubble of hydrogen appears, increases very slowly as the strength 

 of the current diminishes, and, when the current is maintained 

 constant at one-twentieth of an ampere, increases as the concen- 

 tration increases and as the temperature decreases. For equiva- 

 lent solutions of electrolytes having the same positive ion, this 

 lime is practically constant; but it is found to be much larger for 

 potassium salts than for those of sodium and lithium. Theory 

 indicates that the electromotive force required for electrolysis 

 increases, at the outset, with the amount of electrolytic products 

 already separated. But when secondary reactions take place, 

 preventing the continuous accumulation of these products if the 

 electrolysis goes on very slowly, the electromotive force required 



