IO ELECTROCHEMICAL INVESTIGATION OF LIQUID AMALGAMS 



A weighed amount of pure mercury was run into the flask H, which 

 was then nearly filled with a saturated solution of thallous sulphate con- 

 taining about ten grams of ammonium oxalate. The stopper was inserted, 

 care being taken that the cathode and the tube T leading to the flask C 

 were immersed in the mercury. The current was now allowed to run 

 until the desired quantity of thallium had been deposited. The time neces- 

 sary for this could be calculated approximately from the readings on the 

 amperemeter. On breaking the circuit, the amalgam was immediately 

 sucked up into C by cautiously opening the stopcock S 4 . The platinum 

 crucible containing the deposited silver was washed with water, dried at 

 200, and weighed. From the weight of the silver deposited, the concen- 

 tration of the amalgam could be calculated. 



The arrangement employed in transferring the amalgams was essentially 

 similar to that used by Richards and Forbes. Hydrogen, prepared from 

 pure hydrochloric acid and zinc, and purified by passing through four 

 towers containing concentrated potassium hydroxide solution and dry 

 fused potash, was supplied through the tube G. The pipette B communi- 

 cated through A with either the hydrogen supply or the vacuum-pump. 

 The outlet tube of B, terminating in a thick capillary, passed through a 

 tightly fitting rubber stopper into the flask C. (The rubber stopper had 

 been boiled with alkali, thoroughly washed with water and finally covered 

 with soft paraffin.) The flask C was supplied with two side necks. The 

 tube F communicated with the vacuum-pump, while T was bent down 

 and passed to the bottom of the flask H. 



The whole apparatus being thoroughly clean and dry, it was manipu- 

 lated as follows: First ^ 4 , 5\, and S 5 were closed and S 2 and S 3 were 

 opened; the pressure in B and C was reduced to 15 mm. of mercury, and 

 5 6 was closed. The manometer, R, proved that the apparatus was free 

 from leakage. By cautiously opening 5" 5 the system was now filled with 

 hydrogen ; and the exhaustion and filling with hydrogen were repeated 

 three or four times. Care was taken to expel the air in the capillary also 

 by a stream of hydrogen. In order to force the hydrogen through the 

 shallow layer of mercury in the bottom of H, the pressure in H was 

 slightly diminished by suction through S 7 . After the amalgam had been 

 drawn up into C, a rapid stream of dry hydrogen was bubbled through it 

 by opening S 5 and ^3, at the same time maintaining a low pressure in C. 

 This served to dry the amalgam and to mix it thoroughly. After 10 or 15 

 minutes S 2 was closed and the system was allowed to fill with hydrogen. 

 5\ was then opened and B exhausted. By opening S 3 the amalgam could 

 be drawn up into B. S 5 was finally opened and normal pressure restored 

 in B, which was then sealed off at A by using a small blast flame. F was 

 cut with a file and the flask C detached. The capillary tip of the pipette- 



