Chemistry and Physics. 315 



SCIENTIFIC INTELLIGENCE. 



I. Chemistky and Physics. 



1. On some physical properties of argon and helium. — Lord 

 Rayleigh has made a new determination of the specific gravity 

 of argon, using a large volume of the gas separated from atmo- 

 spheric nitrogen by sparking with oxygen. The result obtained, 

 referred to0 2 as 16, was 19-940. Professor Ramsay had previously 

 obtained a density of 19-941 for the gas obtained by the magnesium 

 method, so that it is evident that the products obtained by the 

 two methods are identical. The author has also determined the 

 refractivity of argon and helium, with the results that the refrac- 

 tivity of argon is 0-961, while that of helium is 0'146, compared 

 with air as unity. The result in the case of argon is very unfav- 

 orable to the view that this gas is an allotropic form of nitro- 

 gen. The refractivity of helium is remarkably low, the lowest 

 previously known being that of hydrogen, which is nearly 0*5 that 

 of air. The results of determinations of viscosity were for 

 helium 0*96 and for argon 1*21, referred to dry air. The latter 

 number is somewhat higher than that for oxygen, which has 

 stood at the head of the list of the principal gases in this 

 respect. The author has found by spectroscopic examination that 

 the gas emanating from the Bath springs contains both argon 

 and helium, with probably less than 10 per cent, of the latter in 

 the mixture of the two. Gas from the Buxton springs was 

 found to contain about 2 per cent, of argon, while the presence of 

 helium in this gas in very small quantity was probable, but not 

 certain. The interesting question concerning the existence of 

 helium in the atmosphere was attacked by allowing the greater 

 part of samples of atmospheric argon to be absorbed by water 

 and examining the residues by the spectroscope. It was expected 

 that helium, since its solubility in water is but about one-fifth 

 that of argon, would be concentrated in these residues if it 

 were present. No helium could be detected in this way, and the 

 author concludes that if helium be present in the atmosphere, it 

 must be in very small quantity, probably much less than a ten- 

 thousandth part. — Chem. News, lxxiii, 75. h. l. w. 



2. Mixed double halides of platinum and potassium. — An 

 investigation of the compounds represented by the formula K 2 Pt 

 (CI, Br) 6 , where chlorine and bromine exist in varying propor- 

 tions, has been made by Herty. He found that the products 

 prepared under varying conditions gave no definite relation 

 between the chlorine and bromine, and that none of these sub- 

 stances remained constant in composition after recrystallization. 

 The author therefore arrives at the conclusion that the products 

 are simply isomorphous mixtures of K 2 PtCl 6 and K 2 PtBr 6 . The 

 previous contrary conclusion of Pitkin and of Pigeon may be 

 considered as unfounded in the light of Herty's careful and elab- 

 orate work. — Jour. Am. Chem. Soc, xviii, 142. h. l. w. 



Am. Jour. Sci.— Fourth Series, Yol. I, No 4.— April, 1896. 

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