310 Scientific Intelligence. 



energy is to be effected by means of endothermic reactions which 

 are irreversible at ordinary temperatures. — C. P., cxxvii, 143-160, 

 July, 1898. G, f. b. 



2. On the Homogeneity of Helium. — By diffusion through a 

 pipe stem, Ramsay and Travers separated a volume of helium 

 first into six fractions. The first traction was then pumped 

 into the diffusion vessel, where one-half of it was diffused and 

 'transferred to vessel (1). Fraction No. 2 was then added and 



one-third of the mixture was diffused and transferred to vessel 

 (1). Fraction No. 3 was then added and one-half of the whole 

 diffused and transferred to vessel (2). Fraction No. 4 was then 

 added and one-half diffused and transferred to vessel (3) ; and so 

 on. Four complete fractionations of this sort in the case of air 

 gave at the extreme fractions 17*37 and 22*03 percent of oxygen 

 respectively. When nitrogen was thus used, prepared from 

 ammonium chloride and, sodium nitrite, thirty fractionations pro- 

 duced no variation in density. In the case of helium, repeated 

 fractionations of the gas from samarskite and cleveite gave a gas 

 of density 1*98 and of refractivity 0-1238 as the lightest fraction 

 and a very little pure argon as the heaviest one. Since further 

 diffusion did not alter the density of the lighter fraction, the 

 authors regard it as pure helium. " It appears therefore that 

 helium contains no unknown gas nor is it possible to separate it 

 by diffusion into any two kinds of gas ; all that can be said is 

 that most minerals which evolve helium also evolve argon in 

 small quantity." The authors had hoped to find a gas with 

 density 10 and atomic mass 20 ; since this would form with He = 

 4 and A = 40 a triad like that of F, CI and Mo, 19 : 35*5 : 55. 

 They still regard the existence of such an element as probable. — 

 Proc. Hoy. /Soc, lxii, 316-324, January, 1898. g. f. b. 



3. On the .Properties of Ozone. — By means of liquid air, Laden- 

 burg has condensed ozonized oxygen to a liquid. Then by 

 allowing this to evaporate partially, he has obtained a residue 

 much richer in ozone, since this gas is less volatile than oxygen. 

 So that by repeating the operation, he obtained finally a gas 

 which contained 86*16 per cent of ozone and which had a density 

 of 1*3698 as compared with oxygen, this density being determined 

 from the rate of diffusion. Hence it follows that the density of 

 pure ozone would be 1*456, theory assigning to it 1*5. He finds 

 that ozone is not as soluble in water as has been supposed, 0*01 

 volume only being absorbed at the ordinary temperature and 

 pressure, or 0*00002 part by weight. By condensing ozonized 

 oxygen, allowing the oxygen to evaporate and then ascertaining 

 the temperature at which the residual ozone evaporated, an 

 attempt was made to determine the boiling point of ozone. The 

 oxygen volatilized at —186°, leaving 4 or 5 CC of an almost black 

 opaque liquid, the temperature of which then rose to — 125°, at 

 which point the liquid exploded. This temperature therefore can 

 be taken only as a lower limit. — Per. Perl. Chem. Ges., xxxi, 

 2508-2515, October, 1898. g. f. b. 



