OF THALLIUM, INDIUM, AND TIN 



9 



It was found that the thallium amalgams could be most conveniently 

 prepared by the electrolysis of a solution of thallous sulphate, using a 

 mercury cathode. Addition of ammonium oxalate prevented the formation 

 of peroxide on the anode. The complete apparatus used in preparing and 

 transferring the amalgam is shown in fig. i. 



Hydrogen 



Fig. 1. Apparatus for Making and Preserving Amalgams. 



The amalgams were prepared by electrolysis in the flask H. Connection 

 was made to the mercury cathode by means of glass tube passing through 

 the stopper carrying the wire K. The anode / terminated in a spiral of 

 platinum wire. The anode was inclosed in a small linen bag (not shown 

 in the figure), in order to prevent any peroxide which might be formed 

 from falling on the cathode. The amount of thallium deposited was 

 measured by a silver coulometer included in the circuit. The coulometer 

 was of the form used by Richards and Heimrod. The porous cup was 

 cleaned with concentrated nitric acid and then boiled with many portions 

 of water before use. The anode was a bar of pure silver which had been 

 prepared for use in an atomic weight research. Care was taken to keep 

 the level of the liquid within the porous cup lower than that outside in 

 order to prevent outward filtration. An amperemeter, also in the circuit, 

 served for an approximate measurement of the current strength. 



