Hydrogen from the Anode. 



271 



liquid it became black, and, moreover, that sometimes small 

 particles of this coating were thrown off, rendering the solution 

 in the eudiometer over the anode turbid. But in this case also 

 the ratio of the quantities of hydrogen at the two poles was so 

 nearly constant that this could scarcely be looked upon as an 

 accidental coincidence. The subjoined Table contains the results 

 of my determinations in seven series of experiments. The 

 column headed Cu gives the weight in grammes of metal thrown 

 down in a copper voltameter introduced into the circuit; H_ 

 and H + show the number of cubic centimetres of hydrogen re- 

 duced to 0° and 760 millims. pressure, respectively developed at 

 the negative and positive poles. The columns superscribed Mg 

 denote the quantities of magnesium equivalent, as the headings 

 show, to the copper in the voltameter, to the hydrogen at the 

 negative electrode, to the hydrogen at the positive electrode, and 

 lastly to the sum of the two last mentioned, whilst the final 

 column (Loss) gives the decrease in weight of the positive wire 

 during electrolysis. 



No. 



Cu. 



H_. 



H+. 





Mg. 



Equiv. 

 Cu. 



Found. 



Found. 



*H_. 



Equiv. Equiv. 

 Cu. J H_. 



Equiv. 

 H+. 



Total. 



Loss. 



1 



00780 



27-3 



2712 



9-36 



904 



0-0292 00290 



0-0100 



00390 



0039 



2 



00725 



25-4 



25-7 



807 



8-56 



00272 00275 



0-0086 



00361 



0035 



3 



0-0780 



273 



269 



1106 



8-97 



00292 0-0288 



00118 



00406 



0041 



4 



0-1180 



41-4 



423 



16-8 



141 



00442 00451 



00180 



00631 



0064 



5 



00800 



28-7 



29-4 



132 



9-8 



00300 0314 



0-0141 



00455 



0045 



6 



00700 



245 



24-7 



9-62 



8 23 



00262 0-0264 



00103 



0367 



0036 



7 



00730 



25-6 



24-8 



9-8 



8 26 



00274 0-0265 



00105 



0-U370 



0039 



It follows most unequivocally from this Table, that the loss in 

 weight of magnesium is equivalent to the total hydrogen given 

 off from both poles ; the precipitated copper of the voltameter, 

 on the other hand, is only equal to the hydrogen evolved from 

 the cathode. 



It is seen, moreover, by comparing the columns H+ and 

 -J-H_, that the quantity of hydrogen disengaged from the posi- 

 tive pole is somewhat more than one-third of that given off from 

 the negative wire. In experiments 3 and 5 this excess is greatest ; 

 and as I was especially struck with the larger quantity of black 

 incrustation thrown off in these two experiments, rendering the 

 liquid in the eudiometer particularly cloudy, it occurred to me 

 to seek, in the presence of this black body, the cause of the ano- 

 malous development of hydrogen. I endeavoured, therefore, to 

 isolate it, and succeeded to a certain extent in doing so. If a 

 solution of chloride of sodium be electrolyzed between two mag- 



