‘192 Dr. Faraday’s Experimental Researches in Electricity. 
makes no important difference in the results when thus.ex- 
pressed by equivalents (1140.). 
1138. Thus nitric acid proves to be the best for this purpose: 
its superiority appears to depend upon its favouring the elec- 
trolization of the liquid in the cells of the trough upon the 
principles already explained (905. 973. 1022.), and conse- 
quently favouring the transmission of the electricity, and there- 
fore the production of transferable power (1120.). 
1139. The addition of nitric acid might, consequently, be 
expected to improve sulphuric and muriatic acids. Accord- 
ingly, when the same trough was charged with a mixture of 
200 water, 9 oil of vitriol, and 4 nitric acid, the consumption 
of zinc was at each plate 2°786, and for the whole battery 
111°5 equivalents. When the charge was 200 water, 9 oil of 
vitriol, and 8 nitric acid, the loss per plate was 2°26, or for the 
whole battery 90°4, equivalents. When the trough was 
charged with a mixture of 200 water, 16 muriatic acid, and 6 
nitric acid, the loss per plate was 2°11, or for the whole battery 
84°4, equivalents. Similar results were obtained with my bat- 
tery of twenty pairs of four-inch plates (1129.). Hence it is 
evident that the nitric acid was of great service when mingled 
with the sulphuric acid; and the charge generally used after 
this time for ordinary experiments consisted of 200 water, 4 
oil of vitriol, and 4 nitric acid. 
1140. It is not to be supposed that the different strengths 
of the acids produced the differences above ; for within certain 
limits I found the electrolytic effects to be nearly as the strengths 
of the acids, so as to leave the expression of force, when given 
in equivalents, nearly constant. Thus, when the trough was 
charged with a mixture of 200 water and 8 nitric acid, each 
plate lost 1°854 equivalent of zinc. When the charge was 
200 water and 16 nitric acid, the loss per plate was 1°82 equi- 
valent. When it was 200 water and 32 nitric acid, the loss 
was 2°1 equivalents. The differences here are not greater 
than happen from unavoidable irregularities, depending on 
other causes than the strength of acid. . 
1141. Again, when a charge consisting of 200 water, 43 oil 
of vitriol, and 4 nitric acid was used, each zinc plate lost 2°16 
equivalents; when the charge with the same battery was 200 
water, 9 oil of vitriol, and 8 nitric acid, each zinc plate lost 
2°26 equivalents. 
1142. I need hardly say that no copper is dissolved during 
the regular action of the voltaic trough. I have found that 
much ammonia is formed in the cells when nitric acid, either 
pure or mixed with sulphuric acid, is used. It is produced in 
part as a secondary result at the cathodes (663.) of the dif- 
74 
