Gooch and Gates — Decomposition of Hydrochloric Acid. 443 

 Table II L — Platinum Anode. 



Time 

 min. 



Cur- 

 rent 

 amp. 



N.D.,00 

 amp. 



Poten- 

 tial 

 volt 



Concen- 

 tration: 



parts 

 in 



1000 



Hydro- 

 gen 

 cm 3 



Oxy- 

 gen 

 cm 3 



Ratio of 

 Oxygen 



to 

 Hydro- 

 gen 



Mean 

 for 

 each 

 concen- 

 tration 









Anode area: 



-l-25cm2 









30 



O'lO 



8'0 



4'0 



43-0 



27-6 



2'3 



•083 



•083 



30 



0'05 



4-0 



12-0 



4-3 



14*1 



2'3 



1*63 







30 



o-io 



8'0 



20*5 







26-2 



3-7 



1-41 





30 



0'15 



12-0 



28'2 







38*8 



6'2 



1-59 



•154 



30 



0-05 



4*0 



13-2 



0-86 



15-2 



4-4 



•289 





30 



o-io 



8*0 



21-2 





28-6 



7-1 



•242 





30 



0*15 



12-0 



30-0 







39*4 



10-6 



•268 



•266 



30 



0-05 



4 



14-0 



0-43 



14-4 



4-8 



•333 





30 



o-io 



8-0 



20*8 





25-6 



7-9 



•308 







30 



0-15 



12-0 



28-3 







37' 



11-9 



•321 



•320 



but undeterminable current density upon the silver anode 

 may be important. The ratios obtained with the platinum 

 anode are never higher than those got by the use of the 

 silver anode, and this fact leads reasonably to the use of the 

 platinum anode in solutions of still lower concentration. For, 

 though in the experiments described the protected silver anodes 

 were practically unattackable at the current densities required 

 for the electrolysis of solutions of the concentration employed, 

 when the attempt was made to extend the range of experi- 

 mentation to the electrolysis of solutions of hydrochloric acid 

 of much lower concentration, it was found that the chloride 

 coating of the anode became disintegrated. In the study of 

 solutions of extreme dilution, therefore, it became necessary to 

 i-evert to the use of platinum electrodes, and this we have 

 found to be quite feasible. Table IV gives the details of an 

 experiment upon a solution of the concentration of 0*043 parts 

 in 1000, with a spiral anode and cathode of platinum wire 

 Q.gmm j n di ame ter and 5 cm long, and in the apparatus of fig. 3. 

 The gas evolved at the anode during the first thirty minutes 

 (A) was measured at intervals of five minutes and recorded as 

 oxygen, without correction for the possible presence of inter- 

 mixed chlorine. The experiment was continued similarly for 

 a period of forty-five minutes (B), at the end of which the 

 measured anode gas was withdrawn, washed with sodium 

 hydroxide and measured in a Hempel burette with a conse- 

 quent diminution in volume amounting to 0'5 cm3 on the 

 25'4 cm3 originally found. At the end of another period (C) of 

 forty-five minutes the anode gas was again withdrawn, and 



