70 Scientific Intelligence. 



the value of (u D — l)/d, 0*2634, and for (//— l)/(/r-|-2)tf, 0-163 ; the 

 molecular refraction-equivalents being 11-587 and 7*163 respec- 

 tively. Ethylene at —100° gives 0-62*7 for the value of (jw D — \)/d 

 and 0-384 for (yu 2 — l)/(^ 2 -f-2)^y the corresponding numbers for 

 gaseous ethylene being 0*578 and 0*385. By viewing the incan- 

 descent pole of the electric arc through a column of three inches 

 of liquid oxygen, with a spectroscope having two calcite prisms 

 of 30° and one of 60°, the red potassium lines being used as ref- 

 erence lines, the authors have obtained the absorption Spectrum 

 of this element. In place of the solar line A, a band was observed 

 having a sharp edge on the less refrangible side and fading away 

 gradually on the more refrangible side. The sharp edge did not 

 coincide with the sharp edge of A, the wave length being about 

 7660. No band corresponding with B was observed but through 

 a thickness of 6 inches of liquid oxygen a faint band appeared 

 which had precisely the same character as A, the wave length 

 of its sharp edge being 6905. Liquid oxygen is distinctly blue, 

 this color, apparently not being due to ozone. Ozone at a low 

 temperature explodes with great violence. — Phil. Mag., V, xxxiv, 

 205, March, 1893. g. f. b. 



5. On the Production of Hydrogen Peroxide in the Electro- 

 lyis of Sidphuric acid. — Kuriloff has investigated the produc- 

 tion of hydrogen peroxide and of persulphuric acid when dilute 

 sulphuric acid of different strengths is electrolyzed. He employed 

 for this purpose an apparatus which permitted the separate col- 

 lection ot the products formed at the two electrodes. The hydro- 

 gen peroxide was determined by titration with potassium perman- 

 ganate and the persulphuric acid by adding a known quantity of 

 ferrous salt to the solution and titrating back with potassium 

 permanganate. The results of his experiments are: (1) The 

 quantity of hydrogen peroxide formed is very small ; (2) hydro- 

 gen peroxide and persulphuric acid maybe simultaneously formed 

 at both electrodes, but the peroxide is not always accompanied 

 by persulphuric acid; (3) the formation of both products is 

 intimately connected with the concentration. Persulphuric acid 

 only appears when the solution contains over 1 per cent of sul- 

 phuric acid ; hydrogen peroxide when the concentration is over 

 one per cent ; (4) mixtures containing 3, 47 and 73 per cent of 

 acid respectively behave differently from other mixtures with 

 regard to the amount of peroxide formed when they are electro- 

 lyzed. This is considered by the author to be due to the fact 

 that the composition of these solutions approximates to that 

 required by the hydrates containing (H 2 O) ]50 , (H 2 0) 6 and (H 2 0) 2 

 to each molecule of H 2 S0 4 , since according to Mendeleeff all these 

 hydrates exist in solution. — J. Soc. Chim. Pusse, xxiii, 235 ; J. 

 Chem. Soc. London, lxiv, (ii), 108, March, 1893. g. f. b. 



6. On the Preparation of Pare Phosphoric oxide. — As usu- 

 ally prepared, phosphoric oxide always contains more or less of 

 the lower oxides mixed with it. Shenstone and Beck have 

 proposed to obtain it pure, by passing it in vapor mixed with 



