﻿Electrochemistry of Radioactive Bodies. 645 



than the corresponding ratio for the thorium series, being 17, 

 actinium C can be separated out in a much purer state than 

 thorium C. 



This apparent inconsistency can be explained most easily 

 by assuming that the ratio of the number of thorium B mole- 

 cules to the number of thorium C molecules in equilibrium, 

 is not the same as the ratio of their periods, but greater. 



Marsden and Barratt * found recently that there is a 

 branch product in the thorium series. For every 100 atoms 

 of thorium C emitting a-particles, 65 expel a-particles of 

 range 8*6 cm. and 35 a-particles of range 4*8 cm. 



If the former of these products be the product in the 

 thorium series corresponding to radium Ci and actinium C 

 in the radium and actinium series respectively, then the ratio 

 of the number of molecules of thorium B to that of thorium C 

 is 16 ; if it be the latter, i. <?., the 35 per cent product, this 

 ratio is 30. 



If we assume that the 35 per cent, product is the body 

 corresponding to radium C and actinium G, the anomaly 

 found above disappears, since now the ratio thorium B to 

 thorium G 3 being greater than the corresponding ratio for 

 actinium, it is only to be expected that thorium C would be 

 more difficult to separate out in the pure form than actinium C. 



Summary. 



1. The general electrochemical properties of radioactive 

 bodies are discussed in this paper. It is shown that the 

 deposition of these bodies on platinum electrodes in the 

 ordinary course of electrolysis, or on a metal dipping into 

 an active solution, depends to a large extent on the potential 

 of the electrode. 



2. Radium B, thorium B, and actinium B, possess the 

 same electrochemical properties. Radium C, thorium G, 

 and actinium possess also the same electrochemical 

 properties. With very small electrode potentials G is de- 

 posited almost pure ; as the electrode potential is increased, 

 the amount of B separated with the C increases also. When 

 e ( H g )== — 0'6 V, B and C are deposited in equilibrium amount. 

 With higher potentials chiefly B is obtained. 



3. A relation exists between the E.M.F. Metal/Solution, 

 and the ratio of B to C deposited on the metal dipping into 

 the solution. When the latter is known, therefore, the 

 former is also known. From this relation, the unknown 



* Marsden & Barratt, Tree. Phys. Soc. vol. xxiv. \\ 50 (1011). 



