TRANSACTIONS OF SECTION 15. 611 



MONDAY, AUGUST 23. 

 The following Papers were read : — 



1. Demonstration oj the Preparation and Properties of Fluorine. 

 By Professor E. Meslans. 



M. Meslans, after some introductory remarks referring to the researches of M. 

 Moissan on the preparation of free fluorine, gave a demonstration of the properties 

 of fluorine, and showed experiments illustrating its action on various elements and 

 compounds. 



He carried out these experiments with the aid of a new apparatus, made 

 entirely of copper, except, of course, the lower ends of the electrodes, which, as 

 usual, consisted of platinum. After having remarked that M. Moissan was the 

 first to show that copper vessels may be employed in the preparation of fluorine, M. 

 Meslans went on to describe the apparatus which he had just used, and which was 

 now being utilised with the object of producing comparatively large amounts 

 of fluorine, and for experiments on the possible industrial application of the 

 element, which it is hoped may now become of easy attainment. 



2. The Properties of Liquid Fluorine. 

 By Professor H. Moissan and Professor J. Dewar, F.R.S. 



3. Demonstration of the Spectra of Helium and Argon. 

 By Professor W. Ramsay, F.R.S. 



4. The Peryneahility of Elements of Low Atomic Weight to the RUntgen Rays.^ 



By Joim WADDEiiL, B.A., D.Sc. 



The paper is partly a discussion of data obtained by Gladstone and Hibbert 

 and by myself, and already published, and partly an account of a reinvestigation 

 of the points at issue, 



I have maintained that there is no great difference between the permeability of 

 lithium and sodium, and that it is hardly correct to say that lithium has next to no 

 absorbent action on the Rontgen rays. 



Beryllium and magnesium and boron and aluminium have been also compared 

 as to absorbent power and found to be nearly equal, so that among the elements 

 of low atomic weight (all below aluminium) there is no sudden or rapid rise of 

 absorbent action with atomic weight. 



Experiments intended to elucidate the peculiar granular appearance of coarse 

 powders are also described. 



5. Continuation of Exp)eriments on Chemical Constitution and the Absorp- 

 tion of X Rays. By J. H. Gladstone, D.Sc, F.R.S., and W. Hibbert. 



In the work recorded last year the authors sometimes introduced an alu- 

 minium scale into their photographs for the purpose of giving quantitative coai- 

 parisons of the amount of absorption of X rays due to various substances. They 

 have now endeavoured to estimate the absorption by means of a Lummer-Brodhun 

 photometer. The aluminium scale, when thus examined, showed that the rays 

 absorbed by different thicknesses varied nearly in a logarithmic ratio. 



Determining the absorption of diSerent negative radicles of lithium salts, when 

 the comparison is so made that the amount of substance traversed by the rajs is 



' Published in the Chemical Kens, October 1, 1897. 



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