11** Gooch and Burdick — Electro- Analysis with 



Fig. 2. 



consists of a 35 cm3 cell C made from a thistle-tube. The 

 anode a is a small piece of thin platinum foil, about one centi- 

 meter square, welded to a platinum wire w' which is sealed 

 into the thistle, as shown. The cathode c consists of a disc of 

 gauze or foil, also about one centimeter square, carried by a 

 rod /• of lead glass which is fused into the meshes of the gauze 

 or into a central hole in the foil, an arrangement which gives 

 great rigidity without the use of much platinum. The electri- 

 cal connection between the disc cathode and the shaft, which 

 carries the current, is made by a plati- 

 num wire w". A stand 6' of spring 

 brass holds the cell during the process 

 of electrolysis, and a similar lighter 

 stand (best made of sheet aluminium) 

 serves to support the cell and contents 

 upon the balance pan. In order to show 

 details clearly, the cell is represented 

 in the figure as resting lightly upon 

 this frame. In actual use, the cell is 

 pushed downward as far as possible, and 

 is held rigidly. 



In using this apparatus, the cathode 

 cell is washed, dried, and weighed. The 

 material for analysis, dissolved in about 

 15 cm3 of liquid, is placed in the cell. 

 To prevent possible loss of liquid by 

 spattering, a collar (conical) cut from a 

 funnel or (concave) made from a perfo- 

 rated and split watch-glass, is set upon the rim of the thistle. 

 The glass rod of the cathode is fixed to the motor shaft. The 

 electrical connections are made as shown. The cathode is 

 rotated at about 800 revolutions per minute. 



Electrolysis of Copper Sulphate* with rotating cathode ; 

 cell and disc cathode washed by decantation. 



Copper 

 taken 



Copper 

 taken 



Error 



Initial 

 current 



Approx. 



Time 



grm. 



grm. 



grm. 



amp. 



volt. 



N.D. 100 



min. 



0-1272 



0-1269 



— 0-0003 



2 



5-5 



100 



20 



0-1272 



0-1278 



+ 0-0006 



1-5 



7 



75 



20 



0-1272 



0-1280 



-f 0-0008 



2 



4-5 



100 



20 



0-1272 



0-1270 



— 0-0002 



2 



7 



100 



20 



0-1272 



0-1271 



—o-oooi 



1-2 



5 



60 



20 



Acidulated with H-,S0 4 . 



