for exciting Voltaic Electricity, 147 



was increased; in fact, ihey yielded only 40 measures of gas, 

 or 1*6 cubic inch, which was the quantity discharged by 490 

 grains. 



When 490 grs. of the acid are used in the trough with 

 thirty plates, these by their action should in each cell excite a 

 decomposition, which should evolve 15*75 cubic inches of hy- 

 drogen, and of course the same quantity in the fluid electro- 

 lyzed; whereas only 1*6 cubic inch was evolved. When three 

 times as much acid was used, the quantity of gas disengaged 

 was the same ; so that the loss of electricity was in that case 

 very great, the gas evolved being to that which should have 

 been evolved, provided the whole of the electricity were trans- 

 mitted, as 1*6 to 47*25 or as 1 to 29*5 : of course, these and the 

 following experiments are not given with the view of showing 

 the actual amount of decomposition that may be effected by 

 sulphuric acid, because much depends on the kind of trough, 

 and other circumstances. But as the circumstances under 

 which they were conducted were generally the same, they may 

 be considered as pointing out under similar circumstances the 

 comparative amount of decomposition. 



Sulphate of Copper, — In the experiments with oil of vitriol 

 490 grs. were used as being the equivalent compared to hy- 

 drogen as 10. As blue vitriol is abisulphate and its equiva- 

 lent number 2500, it was necessary to employ 1250, or only 

 half of that number of it in trying its electrolytic power com- 

 pared to that of oil of vitriol under similar circumstances ; but 

 other quantities were also used, so as to ascertain the power 

 of solutions of different strengths. 1250 of the salt dissolved 

 in sixty ounces of water yielded 180 measures of hydrogen. 

 Now the gas given off by using 490 of oil of vitriol, and of 

 course 400 of sulphuric acid, was only 40 ; so that a quantity 

 of sulphate of copper, which contains the same proportion of 

 acid, and of course causing the same destruction of the plates 

 of the trough, yielded 4*5 times as much. When a weaker 

 solution was used, a proportionally greater quantity of gas 

 was set free. 416*6 grs. or £ yielded 82, which multiplied by 

 3 as 246, that is, rather more than six times the quantity given 

 off by a similar proportion of oil of vitriol. 246 measures of 

 the volta-electrometer are equal to 9*6 cubic inches, which de- 

 ducted from 15*75 leaves 6*15, so that the loss amounted to 

 39 per cent. When blue vitriol is employed the action is at 

 first by no means energetic, but it gradually becomes more 

 and more so for about an hour or so, after which it becomes 

 weaker; but it continues for a much longer time than when 

 oil of vitriol is used, the action of which is in general over 

 in less than an hour, whereas that of the other continues for 



U2 



