442 Gooch and Gates — Decomposition of Hydrochloric Acid. 

 Table II. — Anodes of Silver protected by Silver Chloride. 



Time 

 min. 



Current 

 amp. 



Poten- 

 tial 

 volt 



Concen- 

 tration: 

 parts in 

 1000 



Hydro- 

 gen 

 cm 3 



Oxygen 

 cm 3 



Eatio of 

 Oxygen to 

 Hydro- 

 gen 



30 



•05 



11-3 



4-3 



14-9 



3'6 



•242 



30 



•05 



12-5 



0-86 



13-6 



4'0 



'294 



30 



•05 



12-5 



0-43 



14-8 



5-0 



•338 



30 



•10 



21-0 



0-86 



26-1 



6-4 



•245 



30 



•10 



21-6 



0-86 



25-5 



6-7 



•263 



30 



•10 



21-3 



86 



24-6 



8-0 



•325 



30 



•10 



20-3 



0-43 



26-3 



8-3 



•316 



30 



•10 



21-6 



0-43 



25 



8-3 



•332 



30 



•15 



26*6 



4-3 



39-7 



10-5 



•264 



30 



•15 



28-5 



0-86 



375 



11-8 



•315 



30 



•15 



29-5 



0-43 



37'9 



12-5 



•330 



In these experiments the ratio of oxygen to hydrogen, 

 though, within the defined limits, not materially or regularly 

 affected by variations in the strength of current, the potential 

 across the electrodes, or the current density, is seen to increase 

 markedly as the concentration of the solution decreases. Only 

 at the lowest concentration of 0*43 parts in 1000, and with an 

 anode of very limited active area, was the average value as 

 high as that obtained by Douiner. Our results, therefore, are 

 at variance in this respect with those of Doumer. We find 

 that the ratio of the volumes of oxygen and hydrogen evolved 

 in the electrolysis of hydrochloric acid depends directly upon 

 the concentration of the solution ; and further that, at a con- 

 centration of 0*43 parts in a thousand, Doumer's ratio is 

 obtained only when the anode is largely protected from the 

 action of chlorine as well as oxygen. 



This being the case, it is interesting to discover how these 

 results obtained with the protected silver anode may compare 

 with those obtainable by means of platinum anodes for similar 

 concentrations of the solution. In the following table are 

 given the details of experiments made with a spiral of plati- 

 num wire (0*8 mm X5 cm ) used as the anode and solutions of 

 similar concentration. 



It is apparent that for the lower concentrations, 0*86 parts 

 and 0*43 parts in a thousand, the ratios of the volumes of 

 oxygen or hydrogen are, in the average, but slightly lower 

 than those obtained when the protected silver anode is 

 employed. For the higher concentration, 4*3 parts in a 

 thousand, the ratio proves to be much lower than that obtained 

 with the silver anode, possibly because, at the higher 

 concentration of the acid, the effect of the very much higher 



