GOG 



Mr. W. A. Borodowsky on Absorption of 



published by S.J.Allen*. This deals chiefly with the secondary 

 radiation emitted by solids, solutions, and pure liquids when 

 ft rays from radium fall on them, but also gives some results 

 of the absorption of /3 rays by liquids. Ke obtained some 

 remarkable results with organic liquids, and attempts to 

 explain them on the view that the arrangement of the mole- 

 cules in the substance has some effect on the secondary 

 radiation and absorption. 



J. A. Crowtherf, on the other hand, found that for solid 

 bodies the absorption of j3 rays from uranium for any particular 

 element is quite independent of its state of chemical com- 

 bination. 



In the present paper the following questions are con- 

 sidered : — 



1. Does the absorption of /3 rays depend upon the physical 

 or chemical state of the solution ? 



2. Does the absorption in liquids take place according to 

 the same laws as in solids ? 



3. Is the absorption of (3 rays by complex substances 

 additive ? 



Experimental Arrangement. 

 *52 mgr. of radium bromide in radioactive equilibrium was 

 used as a constant source of /3 rays. It was contained in a 

 copper capsule with an air-tight mica window. All the a rays 



Fi ; r. 1. 



were stopped by the mica, but the /3 and 7 rays readily 

 passed through into a small ft ray electroscope, which was 

 placed above the radium at a distance of about one centi- 

 metre from it. In some experiments the solutions and liquids 

 examined were contained in a glass cell and in others in a 

 glass wedge (figs. 1 and 2). 



* Phvs. Rev. 1909, vol. xxix. p. 177. 



t Phil. Mag. 1906, vol. xii. p. 379, 



