150 Dr. Fyfe on the Employment of Iron 



making the loss in the former amount to about 16, and in the 

 latter to about 20 per cent. 



But in this case, where nitric acid was added to the sul- 

 phuric, with the view of increasing the power, the expense 

 was considerably increased. When sulphuric acid alone was 

 used, there was much less electrolyzation indicated by the 

 volta-electrometer. For each equivalent of water decomposed, 

 4 66 of zinc in each plate, with of course a corresponding 

 quantity of acid, were consumed ; so that the loss of electro- 

 lytic power amounted to about 78 per cent. The loss was 

 therefore less ; in other words the electrolyzation was greater. 

 But this, though it alters the comparative expense, yet it does 

 so in a small degree ; because, if the electrolytic action in this 

 trough is greater with sulphuric acid, it will be greater also 

 with the metallic solutions. But even allowing that it is so 

 to a trifling extent, it has been shown that the comparative 

 powers of oil of vitriol and of the mixed salts are as 1 to 8, 

 and their expense as 2 to 1 ; so that if we suppose the electro- 

 lytic power with oil of vitriol in the experiments I have re- 

 corded as amounting to about 10 per cent., and that in Fara- 

 day's trough, with the same acid, as about 22 per cent., or 

 rather more than double, this would reduce the power of the 

 same trough with the mixed salts, compared to its power with 

 oil of vitriol, to about as 4 to 1, which would make the ex- 

 pense for the same amount of electrolyzation very nearly the 

 same in both cases. Viewing it in this light, still there would 

 be a saving, because the same electrolytic action would be ob- 

 tained, with less destruction of the trough, and consequently 

 the trouble and expense would thus be diminished. 



The peculiar condition into which iron is brought by the 

 action of nitric acid, as discovered lately by Schcenbein, and 

 proved also by Faraday and others*, seemed to exclude the 

 prospect of its being used in the construction of voltaic troughs; 

 but considering the ease with which it is acted on by sulphate 

 of copper, I was induced to try it, in the hopes that the state 

 of inaction does not depend on the want of power in the iron 

 to convey the electric agent, but on some other cause, brought 

 into play by the action of the acid. I accordingly had a 

 trough constructed of copper and sheet iron, the plates being 

 of the same number and size as those in the zinc battery. 

 When diluted acid was poured into it, a smart electrolytic 

 action took place, accompanied by the discharge of gas in 

 the volta-electrometer; but in the course of a short time the 

 action became feeble, and though it went on for some time, 



* See various papers in our last three volumes.— Edit. 



