564 



MR. F. E. SMITH, MR. T. MATHER, AND DR. T. M. LOWRY 



acid solution usually gives a lower deposit of silver than a neutral one (p. 595), and in 

 consequence the results with the porous pot form were at first more variable and 

 lower than with the Rayleigh form. In addition, some cyanide may have been 

 present in solution. More consistent results were obtained on prolonged soaking, but 

 we found the most satisfactory treatment was to place the pot in an electric furnace 

 for a few hours. This procedure was adopted in our later observations, and the mean 

 of the values resulting from these is given separately (Tables III. and IV.). The 

 final result, 1 '11828, is practically the same as that obtained for the Rayleigh form, 

 and we conclude that the porous pot in our form of voltameter is of no advantage. 



TABLE III. Richards Form. Absolute Determinations. 



* Porous pots baked in electric furnace after soaking in water. 



t Porous pots soaked in acid and afterwards in water for several days. 



TABLE IV. Comparison of the Richards Form with the Rayleigh Form. The latter 

 is taken as the Standard (1 Coulomb deposits I'll 8 27 Milligrammes of Silver). 



* Porous pots baked in electric furnace after soaking in water. 



t Porous pots soaked in acid and afterwards in water for several days. 



