Geology and Mineralogy. 301 



when a mixture of an excess of oxygen with hydrogen is suffi- 

 ciently fractionated, pure oxygen is obtained on the one hand, while 

 on the other hand a mixture of one part of hydrogen with four 

 parts of oxygen diffuses unchanged, the authors have calculated 

 that if helium consists of a mixture, it is composed either of two 

 gases of the densities 2'366 and 1*874 or of two with the densi- 

 ties 2-133 and 1-580. 



The authors finally mention what they consider a possible 

 explanation of this behavior of helium, in that the heavy mole- 

 cules may have been separated from lighter molecules of the same 

 gas. They state that the idea that all the molecules of a gas are 

 homogeneous has never been submitted to the test of experiment, 

 and they believe that this question deserves further study. — 

 Comptes Rendus^ cxxiii, 214. h, l. w. 



4. Argon and Helium from a Natural Spring. — Ch. Moureu 

 has examined the gas from a spring at Maizieres (Cote-d'Or), and 

 has found it to contain a small quantity of oxygen, about 2 per 

 cent, the remainder showing the negative characters of nitrogen. 

 After the absorption of nitrogen by metallic lithium, a remark- 

 ably large residue remained, amounting to between ^Jg^ and yV ^^ 

 the total volume, giving the characteristic spectrum lines of argon 

 and helium. — Bull. Soc. C/iim., xv, 626. h. l. w. 



5. The liquefaction of helium. — Olszewski, working upon a 

 sample of helium gas obtained by Ramsay from the mineral cleve- 

 ite, has found that it remains permanent even under the most 

 extreme conditions as to temperature and pressure available. In 

 one series of experiments the helium, confined under a pressure of 

 125 atmospheres, was cooled to the temperature of oxygen, boil- 

 ing first under atmospheric pressure (— 182°'5) and then under a 

 pressure of 10™™ of mercury ( — 210°). In neither case did it con- 

 dense, nor was there any indication of liquefaction even when the 

 gas was expanded till the pressure fell to one atmosphere. In 

 the second series of experiments liquid air boiling at 10™™ of 

 mercury (about —220°) was employed, the helium being under a 

 pressure of 140 atmospheres; but here also the results were nega- 

 tive. Theoretical calculations, based upon the formula of Laplace 

 and Poisson for change of temperature under adiabatic expansion, 

 led to the conclusion that the boiling point of helium lies below 

 — 264°, or at least 20° lower than the values obtained by 

 Olszewski for hydrogen. The higher density of. helium, however, 

 would lead one to expect that the boiling point would also be 

 above that of hydrogen. — iVa^i^re, liv, 377. 



11. Geology and Minekalogy. 



1. Glacial deposits, preglacial valleys, and interglacial lake- 

 formation in Suhalpine Switzerland. — Dr. 0. S. Du Riche 

 Preller read an interesting paper with the above title before 

 the Geological Society of London in May last. The conclusions 

 he reached after a careful examination of the evidence, particu- 



