148 Dr. Fyfe on the Use of Sulphate of Copper 



eight or ten hours, indeed sometimes much longer, though 

 of course very feeble. I have occasionally observed the trough 

 in action at the expiration of thirty-six hours. 



Nitrate of Copper. — The electrolytic action of nitrous acid, 

 as is well known, being more powerful than that of sulphuric 

 acid, naturally led me to try the effect of nitrate or rather bi- 

 nitrate of copper in the cells of the trough. Using half of its 

 equivalent, I found that the quantity of gas in the volta- 

 electrometer, was much greater than when sulphate was em- 

 ployed, showing that by means of it there was a greater trans- 

 mission of electricity. But as the use of the nitrate is pre- 

 cluded, owing to its expense, I was induced to try what effect 

 the addition of other salts, such as a nitrate, would have, either 

 by causing the decomposition of the sulphate, and its conver- 

 sion into nitrate, or perhaps by increasing the conducting 

 power, and consequently admitting of the more ready trans- 

 mission of the electrolytic agent. 



Sulphate of Copper and Nitrate of Potass, — Nitre was the 

 salt to which I first had recourse, two equivalents of which 

 are necessary for the decomposition of one of blue vitriol. 

 In using this mixture I found that the power was increased, 

 but the results were not always the same; in some they were 

 as 40 to 57, in others as 40 to 53. Using 1250 of blue vitriol 

 and 1040 of nitre, dissolved in sixty ounces of water, the gas 

 given off amounted on an average to 330, or 13*2 cubic inches. 

 The quantity that ought to be given off, supposing the whole 

 of the electricity transmitted, is 15*75, so that there was in 

 this case a loss of about 16 per cent., whereas when blue vi- 

 triol alone was used, under similar circumstances, the loss 

 amounted to 39 per cent. With oil of vitriol the loss was 90 

 per cent. 



Sulphate of Copper and Sea Salt, — Having found the in- 

 crease in electrolytic action of the sulphate by admixture of 

 nitre I was next induced to try it with sea salt, using them in 

 the proportion of 1250 to 600. When these quantities were 

 employed dissolved in sixty ounces of water, the gas collected 

 in the volta-electrometer very nearly amounted to that given 

 off by the mixture of sulphate and nitre. It was generally 

 about 310, compared to the other as 330; so that it yielded 

 12*4 cub. inch. The deficiency therefore was 3*35 or 21 per 

 cent. 



Though by the use of sulphate of copper, particularly when 

 mixed with other salts, there is little loss of electricity, it is 

 of importance to ascertain their expense, compared with that 

 of oil of vitriol, as indicated by the above experiments. The 

 commercial price of blue vitriol is to that of oil of vitriol as 



