Chemistry and Physics. 499 



SCIENTIFIC INTELLIGENCE. 



I. Chemistry and Physics. 



1. On Hyponitrous acid and Hyponitrites. — According to 

 Kieschner's investigations, the hyponitrites may be prepared 

 readily from potassium oxyimidosulphonate. Fifty grams of this 

 salt is dissolved in 35 cc of boiling water. After cooling by means 

 of ice, the solution is mixed with 10 cc of a concentrated sodium 

 hydrate solution (1 : 1), the temperature of the mixture not being 

 allowed to rise above 30°. After cooling to 10°, 90 cc more of the 

 sodium hydrate solution are added, the mixture is heated to 50° for 

 half to three-quarters of an hour, and is then poured into a liter 

 of water. This solution contains sulphate, sulphite and hypo- 

 nitrite of sodium and also a little undecomposed oxyamido-salt 

 and some hydroxylamine. By adding yellow mercuric oxide, 

 these last substances are destroyed. The liquid, after filtering, is 

 made up to four liters and silver nitrate is added so long as a 

 light yellow precipitate, consisting of silver hyponitrite, is pro- 

 duced. By the addition of barium, strontium or calcium nitrate 

 to a strongly alkaline solution of silver hyponitrite, a precipitate 

 is obtained of the corresponding hyponitrite. It is washed with 

 alcohol and ether and dried on filter paper. All of these salts are 

 slightly soluble in water, have an alkaline reaction and evolve 

 nitrous oxide with acids. The calcium salt is the most stable. It 

 loses its crystal water with difficulty and is not affected at the 

 ordinary temperature by carbon dioxide. They are represented 

 by the formulas Ba(NO) 2 . (H,0) 4 , Sr(NO) 9 . (H 2 0) 6 and Ca(NO) 2 . 

 (H 2 0) 4 respectively. On adding lead acetate to the sodium salt 

 in alkaline solution, a yellowish-white precipitate of basic lead 

 hyponitrite is produced ; which on treatment with acetic acid 

 yields the normal salt Pb(NO) 2 , as a yellow crystalline powder, 

 which explodes on heating. Copper sulphate added to sodium 

 hyponitrite gives, on treatment with ammonia, a green amorphous 

 powder having the composition Cu(NO) 2 . Cu(OH)„. Silver hypo- 

 nitrite Ag 2 (NO) 2 is obtained in crystals from a strong ammonia 

 solution. It is decomposed by hydrogen chloride, yielding hypo- 

 nitrous acid. The free acid does not decolorize an iodine solution 

 nor does it set free iodine from potassium iodide. Bromine oxi- 

 dizes it to nitric acid, though the reaction is not a quantitative 

 one. — Zeitschr. anorg. Chem., xvi, 424-437, 1898. g. f. b. 



2. On Experiments with Helium. — It has been shown by 

 Travers that when an electric discharge is passed through a 

 Pliicker tube containing helium at a pressure of about three milli- 

 meters, the electrodes being of platinum, a reddish-yellow glow at 

 first appears, which, passing through shades of yellow and green, 

 finally becomes the phosphorescent glow characteristic of a 

 vacuum. Evidently these changes are due to the gradual absorp- 

 tion of the helium by the platinum which has been deposited by 



