hostetter: electrolytic reduction of iron 



431 



longer until the last of the iron is reduced. In this manner, the 

 iron left in the anode chamber at the end of the electrolysis is 

 reduced to 0.1 to 0.3 mg. A siphon connecting the two chambers 

 was also employed to lessen this diffusion. The large currents, 

 however, caused so much heating in the siphon tube that its use 

 was abandoned in favor of the above scheme. 



Of the materials tested for suitability as porous cells, the un- 

 glazed ]\Iarquardt porcelain crucibles (20 cc.) seem to answer 

 best. To keep spray from the anode out of the cathode chamber, 



TABLE I 



Ferrous Ammonium Sulfate 



TABLE II 

 Electrolytic Reduction of Ferric Ammonium Sulfate Solution 



the top of the crucible is covered with a funnel of the same dia- 

 meter. The anode lead is brought down thru the stem. The 

 funnel is clamped over the crucible with a frame of glass rod; 

 tension is secured with rubber bands. Oxygen escapes thru a 

 lateral hole in the funnel stem. The anode is of Pt foil with an 

 effective area of some 28 sq. cm. / 



The Method. The ferric (sulfate) solution (volume 300 cc.) is 

 placed in the gold dish (cathode) and 10 cc. sulfuric acid (1.84) 



