Chemistry and Physics. 431 



the mean value obtained being 2*31 X 10~ 7 . To ascertain whether 

 at equal concentrations, the ratio of dissociation is the same in 

 the gaseous and in the dissolved state, the author quotes Natan- 

 son to the effect that at 0° and a pressure of 250 mm ten per cent 

 of the peroxide is dissociated. Under these conditions, the abso- 

 lute density of the gas is 0-0014; i. e., it corresponds to a 0*14 

 per cent solution of peroxide in a vacuum. From Cundall's ex- 

 periments it appears that a 1'44 per cent solution at 0° contains 

 0-274 per cent of dissociated peroxide; and by Van 't Hoff's law 

 a 0*14 per cent solution would contain only about one per cent of 

 dissociated peroxide. In the gaseous state therefore the dissocia- 

 tion is so much farther advanced than it is in the chloroform 

 solution, that to reach the effect of a vacuum the solution must 

 be diluted to more than one hundred fold the bulk of the gas. — 

 J. Ghem. Soc, Ixi, 242, March, 1892. G. F. B. 



4. On a new method of preparing Carbonyl Sidpliide. — When 

 carbonyl chloride is passed over heated cadmium sulphide, Ntjr- 

 icslisr has observed that carbonyl sulphide is formed. The car- 

 bonyl chloride must be carefully dried by passing it through sul- 

 phuric acid, and the finely divided cadmium sulphide contained 

 in a hard glass tube, is to be mixed with asbestos to increase its 

 surface. Although the action is perceptible even at ordinary 

 temperatures, the author found that the best results were ob- 

 tained at 360° to 280°. The gas evolved under these circum- 

 stances contained 94*87 per cent carbonyl sulphide, 3-98 per cent 

 carbon monoxide and 1/15 per cent air. The tubes contained 

 brilliant crystals which on analysis were found to be cadmium 

 chloride. The reaction appears, therefore, to be a simple double 

 decomposition according to the equation COCl„ + CdS = COS + 

 CdCl 2 .— Ber. Bert. Ghem. Ges., xxiv, 2967, October, 1891. 



G. F. B. 



5. On the Preparation and Properties of Ccesium. — Beketoff 

 has observed that caesium is readily prepared by the action of alumi- 

 num upon its hydroxide. On heating 114 grams of the hydroxide 

 with 27 grains of aluminum in a nickel retort and collecting the 

 distilled metal in glass receivers, he obtained 25 grains of the 

 metal. Its heat of combination with water was found to be from 

 50 to 52 calories. Caesium hydroxide was prepared by precipita- 

 ting pure sulphate with barium hydroxide and concentrating the 

 filtrate in a silver dish placed a metal retort. On fusion, the dish 

 was slightly attacked. It has a density of 4*0178 and a molecular 

 volume of 37*3. Its heat of solution in water is 15876, which is 

 higher than that of the other alkali hydroxides. Its heat of neu- 

 tralization with hydrogen chloride is 13790. — Bull. Acad, St. 

 Petersbourg, II, ii, 169, 171 ; J. Ghem. Soc, Ixii, 274, March, 1892. 



G. F. B. 



6. On the Color of Cobcdt- Solutions. — Etard has shown that 

 the solubility-curves both of cobaltous chloride and cobaltous 

 iodide consist of two portions intersecting at about the point 

 where with increasing concentration the color changes. Hence 



