432 Scientific Intelligence. 



were fitted rather tightly into this tube, so as to make good 

 contact with the walls of the tube and with each other. The 

 tube was then placed upright in the solution to be examined, its 

 lower end being immersed two or three centimeters deep, and it 

 was allowed to remain in this position until the fifth roll of paper 

 was completely moistened by the rising liquid ; requiring from 

 3 to 4 days. To ascertain the composition of the liquids at the 

 several levels, the tube was cut across opposite the ends of the 

 adjoining rolls, and the rolls separately extracted with water. 

 Using a solution containing 10 grams sodium chloride and 10 

 grams barium chloride in 100 c. c. water, the authors found the 

 ratio of Bad, to NaCl to be in the fifth roll 1 : 1-364, in the third 

 1 : 1*230 and in the first 1 : 1*022 ; showing the greater diffusibility 

 of the sodium chloride. With a solution of 10 grams crystallized 

 ammonium-ferrous sulphate in 100 c. c. water, 87 hours were 

 required to reach the sixth roll, and the ratio of the Fe to the 

 NH 3 , which in the double salt is 1 : 1, was found to be in the 

 4th roll 1 : 1*686. When a saturated solution was used, the 

 ratio in the fourth roll, after 96 hours, was only 1 : 1*004, and in 

 the fifth 1 : 0*993. Potassium-ferrous sulphate and potassium- 

 nickel sulphate gave similar results ; a considerable dissociation 

 taking place in dilute solutions, while in saturated solutions it is 

 scarcely appreciable. Further experiments showed that aqueous 

 solutions of the double chlorides of mercury with sodium and with 

 lithium are decomposed by diffusion, while alcoholic solutions are 

 not ; and that the ammonium double chloride is permanent even 

 in aqueous solution. No splitting was observed with the double 

 salts HNa(NH 4 )P0 4 (H 2 0) 4 , (KCy, AgCy), and KNaC 4 H 4 G & 

 (H„0) 4 in aqueous solution ; but the compound of sodium chloride 

 with grape sugar (C 6 H 12 6 ) 2 NaCl is partially dissociated. No 

 decomposition was observed with naphthalene picrate or methyl- 

 ketol picrate. Making a comparative experiment with Rtidorff's 

 apparatus, the authors found that though the dissociation was 

 more effective in a given time with ammonium-ferrous sulphate and 

 with the sodium chloride compound of grape sugar by the mem- 

 brane diffusion method, the filter paper method was the better for 

 the sodium mercuric chloride. — Ann. cl. Chem., cclxxii, 156, 1892. 



G. F. B. 



5. On Chemical Inactivity at loio Temperatures. — Some in- 

 structive experiments have been made by Raoul Pictet confirm- 

 ing his view that all chemical action ceases at very low 

 temperatures. Sulphuric acid solidifying at —56° and containing 

 89 per centH 2 30 4 was brought into intimate contact, in the solid 

 condition and at a temperature — 125°, with finely powdered 

 sodium hydroxide, at the same temperature. No chemical action 

 took place between them even when strongly compressed. Even 

 when electric sparks were passed through the mass, no effect was 

 produced except in the line of the sparks. On warming to — 80° 

 action suddenly began, evolving great heat and fracturing the 

 vessel. With a weaker acid containing 35 per cent H 2 S0 4 



