Chemistry and Physics. 427 



boiling point of mercury itself being 359. — Ber. JBerl. Chem. Ges., 

 xxiv, 729, March, 1891. g. f. b. 



3. On Hydr azoic Acid. — Further observations upon azoimide 

 or hydrazoic acid N 3 H, have been published by Cttrtius in con- 

 nection with Radenhausen. They have succeeded in isolating 

 the anhydrous gas in the pure state and find that it is permanent 

 only at temperatures above 37°. Below this even at the atmo- 

 spheric pressure it condenses to a clear colorless mobile liquid, 

 w 7 hich is highly explosive, and which possesses the intolerable 

 odor of the gas. The liquid is readily miscible with water or 

 alcohol. On fractionating the concentrated aqueous solution four 

 times, an acid was obtained containing over 90 per cent of N 3 H. 

 From this the last traces of water were removed by means of 

 fused calcium chloride. The anhydrous liquid thus obtained is 

 found to boil at 37°. When suddenly heated, it explodes with 

 extraordinary violence with a vivid blue flame. In a Torricellian 

 vacuum it explodes spontaneously at the ordinary temperature ; 

 the explosion under these circumstances of only five centigrams 

 being sufficient to pulverize the apparatus completely, driving 

 the mercury in the form of dust into every corner of a large 

 laboratory. On one occasion, about 0*7 gram suddenly exploded 

 on removing the tube containing it from a freezing mixture in 

 which it had been immersed. Every glass vessel in the vicinity 

 was completely shattered by the concussion and one of the 

 authors was seriously injured. By determinations of its conduc- 

 tivity, Ostwald finds this acid to be a little stronger than acetic 

 acid. Moreover, the authors have not succeeded in effecting the 

 change of the ammonium salt N 3 NH 4 into an isomeric substance, 

 as suggested by Mendeleef. The ammonium salt itself crystallizes 

 in fine large prisms, which grow continually smaller and finally 

 disappear, by continuous sublimation. — Nature, xliii, 378, Feb. 

 189]. G. F. B. 



4. On the Production of Arabinose from Wheat bran. — 

 Steiger and Schtjlze have shown that, when wheat bran, freed 

 from starch and albuminous matter, is boiled for several hours 

 with a three per cent sulphuric acid, the acid removed by barium 

 carbonate, the solution filtered, evaporated and extracted with 

 alcohol, there crystallizes out arabinose on evaporation of the 

 alcohol. It is probably formed by the hydrolysis of metaraban, 

 a constituent of the cell membrane which cannot be obtained 

 pure but which gives a cherry-red color on warming with hydro- 

 chloric acid and phlorogiucinol. — Ber. Berl. Chem. Ges., xxiii, 

 3110, October, 1890. G. f. b. 



5. On distinguishing Arsenic from Antimony. — Deniges pro- 

 poses to distinguish between the deposits of arsenic and antimony 

 by the fact that if the stain obtained by Marsh's test is placed 

 in a porcelain capsule and heated with a few drops of pure nitric 

 acid, and then treated with a small quantity of ammonium molyb- 

 date dissolved in nitric acid, the antimony deposit gives no pre- 

 cipitate while arsenic forms arseno-molybdic acid which separates 



