620 Prof. T. Godlewski on the Action of 



newly-formed atom will readily be expelled from the 

 aggregate on account of the reaction following upon the 

 emission of an « particle. In consequence of this, the 

 groups of hydrosols of RaA, travelling towards the anode, 

 will contain only atoms of RaA, and they will not carry 

 with them atoms of RaB. The latter, after suitable coagu- 

 lation, will produce positive hydrosols and will deposit them 

 at the cathode. 



It is otherwise with RaC. When the atom of RaC arises 

 from RaB the reaction is extremely feeble, RaB emitting 

 only the j3 particle. For this reason, if one of the atoms in 

 the aggregate RaB which forms the centre of a positive 

 hydrosol. is transformed into RaC, it will not escape from its 

 environment of remaining RaB atoms, which form a positive 

 hydrosol, but will be carried with them to the cathode. We 

 then get an aggregate similar to that which is obtained by 

 mixing two colloids of opposite signs when one of the 

 two is in considerable excess. In this case no precipitation 

 occurs, but the colloid which is in small quantity becomes 

 oppositely electrified, taking the charge of the colloid which 

 is in excess *. Something of the kind takes place here. 

 We may therefore expect that those RaC atoms only go 

 to the anode which during their transformation managed to 

 escape from the aggregate RaB ; and also those which 

 belong to groups in which the majority of the RaB atoms 

 have already undergone transformation. The groups in 

 which so many RaC atoms have arisen that through their 

 presence the charge of the remaining RaB atoms has become 

 neutralized, must be precipitated : they may become fixed to 

 the walls of the vessel ; at any rate they are not carried with 

 the electric current. The groups containing an excess (with 

 respect to charge) of RaB over RaC will go to the cathode. 

 Then follows the appearance of RaC at the cathode, though 

 it forms negative hydrosols. 



The results of further investigation on the subject of the 

 action of colloids on radioactive products in solution confirm 

 abundantly the hypothesis which has here been brought 

 forward. 



2. Interaction of Colloids. 



After establishing that radioactive products in solution are 

 in the colloid state, I investigated the influence of foreign 

 colloids upon these products. This subject has hitherto 

 received but scant attention : we can only mention one 



* Zsigniondy, ' Kolloidchemie/ p. 58. 



