Chemistry and Physics. 319 



SCIENTIFIC INTELLIGENCE. 



I. Chemistry and Physics. 



1. The Gases produced by Actinium. — It is known that solu- 

 tions of radium salts give off continuously a mixture of hydrogen 

 and oxygen from the decomposition of water, and it has been 

 found that this detonating gas contains a small quantity of 

 helium which is believed to be a product of the disintegration of 

 the radium atom. Debierne has recently confirmed this behavior 

 of radium by using nearly a tenth of a gram of Curie's radium 

 bromide and operating in a manner similar to that of Ramsay 

 and Soddy. He has found, further, that solutions of actinium 

 salts give off detonating gas containing helium, and that the 

 amounts of these products apparently correspond to the amounts 

 produced by a quantity of radium having the same activity. 



For the experiments with actinium he used the whole of his 

 most active products, and obtained the same results with a por- 

 tion which had been specially purified from any possible contami- 

 nation with radium by adding to it barium chloride and removing 

 the barium. It was found, moreover, that the barium thus re- 

 moved did not contain an appreciable quantity of radium. It 

 was found also that solid actinium fluoride gave off helium. 

 Debierne states that in addition to the large quantity of emana- 

 tion with a rapid rate of decay which is given off by solid salts 

 of actinium, there comes from it a very small quantity of an 

 emanation of much slower change which he has identified as 

 identical with the radium emanation ; but its quantity is too 

 small to have produced the helium found in his experiments. — 

 Comptes Rendus, cxli, 383. h. l. w. 



2. A JVeio Heavy Solution. — Duboin has prepared some 

 liquids analogous to the well-known Thoulet's solution, one of 

 which, at least, appears to possess decided advantages over the 

 latter. In the place of the potassium iodide used by Thoulet, 

 he uses sodium or lithium iodide. The alkaline iodide and mer- 

 curic iodide are alternately added to a small quantity of water 

 until saturation takes place, the temperature being slightly raised 

 at the end of the operation. Then the liquid is allowed to cool, 

 and after twenty-four hours it is filtered. It was found that 

 Thoulet's solution prepared in this way, and filtered at 22-9°, 

 gave a specific gravity of 3*196 and an index of refraction of 

 1*730, while the sodium mercuric iodide solution, filtered at 

 2475°, gave a density of 3*46 and an index of refraction of 1*797. 

 The lithium solution is intermediate in its density and refraction 

 between the two just mentioned. Analyses of the solutions 

 showed that their compositions corresponded closely to the 

 formulas K 2 HgI 4 , Na 2 HgI 4 and Li 2 Hgl 4 , and in each case the 

 amount of water present was somewhat more than 10 per cent. 

 A similar ammonium mercuric iodide solution was prepared, but 

 this was less dense than Thoulet's liquid. 



