Voltaic Batteries^ 8^c. 137 



77. The comparative effects of these different acid solutions 

 were then sought for under two distinct modifications of the 

 experiments as just stated : first, when the elementary plates 

 of the couple used were of a different size from those by which 

 the results in the above table had been obtained ; and secondly, 

 when the two plates of the couple were placed at a different 

 distance from one another than that stated above ; but whilst 

 every other attendant circumstance, in either case, was main- 

 tained precisely the same as at first. 



78. For the former purpose a smaller couple was taken 

 and immersed in the different acid mixtures successively, as 

 before ; when the weight of zinc lost, in the same time, was 

 of course less in the aggregate than when the larger couple 

 was employed ; but the difference between the amount of loss 

 occasioned by the different acid mixtures was precisely after 

 the same rate as had been previously determined for thejother 

 couple, and as that rate is stated in the fourth column of the 

 above table. 



79. And when a couple was employed of the same size as 

 the first (75.), but with its plates placed at a greater distance 

 from one another than in either of the previous instances, in 

 like manner to the last, the action in the aggregate was re- 

 duced by reason of the greater distance, but the comparative 

 rate at which each acid mixture acted upon this couple was 

 precisely the same as had already been found in the two pre- 

 vious instances. 



80. It appears, therefore, that the comparative effects of 

 these different acid solutions are the same whatever may be 

 the size of the voltaic couple, or whatever may be the distance 

 between its elementary plates ; and the above table, therefore, 

 represents the comparative rate in which dilute sulphuric 

 acid of different degrees of strength acts upon any voltaic 

 arrangement. 



81. A review of this table shows, 1st, that the greatest 

 amount of action induced in any arrangement by dilute sul- 

 phuric acid takes place when the mixture is in the proportion 

 of about 15 parts by measure of ordinary acid, and 100 of 

 water; or of the average specific gravity of 1*140: 2ndly, 

 that the rate of increase of action is neither the same as the 

 rate of increased proportions of the acid, nor of the specific 

 gravity of the mixture, but occurs in some other simple rate, 

 bearing however no very obvious relation to any apparent at- 

 tendant circumstances. 



82. The acid mixtures which will subsequently be employed 

 in these experiments are the first four of the above table. 



