f 



GALVANISM. 353 



the substance to be submitted to Voltaic action. Let them each be filled with 

 purified water, and connected by asbestos. If A be connected with the posi- 

 tive and S with the negative wire, it was expected that any acid constituent 

 which may be in the substance of which S is formed would pass into A, which 

 would become an acid solution, and appear by the application of the usual 

 tests. If, on the other hand, A be connected with the negative and S with the 

 positive wire, any alkali which may be in the substance of which S is formed 

 was expected to pass into A, and to be manifested there by the common alka- 

 line tests. 



In the first case in which his method was tried, the cup S was formed of 

 sulphate of lime. The cup A was connected with the negative and S with the 

 positive wire. With a battery of 100 pair of plates, the water in A was in 

 about four hours converted into a strong solution of lime, and the liquid in S 

 was converted into sulphuric acid. When the cup A received the positive and 

 S the negative wire, the effects were reversed. In that case, the water in A 

 became sulphuric acid, and a solution of lime was found in S. 



Other saline cups were submitted to the same process with like results ; the 

 water in the positive cup always receiving acid, and that in the negative cup 

 alkali. 



Two cups of glass were connected with the poles of the battery. One was 

 filled with distilled water, and the other with a saline solution. In every case 



as 



cess sulphate of lime, sulphate of strontia, fluate of lime, sulphate of baryta, 

 and other insoluble salts, and in each case obtained the acid in the positive 

 ami the base in the negative cup. Certain mineral substances, such as basalt, 

 zeolite, and vitreous lava from ./Etna, were examined ; and although the saline 

 ingredients in some cases prevailed in extremely minute proportions, their 

 presence was, nevertheless, distinctly manifested. The soluble compounds, 

 such as sulphate and nitrate of potash, sulphate and phosphate of soda, were 

 easily decomposed, and the results were the same. 



The metallic salts deposited their metallic elements in crystals on the nega- 

 tive wire, round which the oxide was also deposited, while the acid was col- 

 lected in the positive cup. 



These, however, were only the first and least important of the consequences 

 of the idea of extending the principle in virtue of which the Voltaic wire cor- 

 roded the glass. We shall dismiss this for the present, to consider the next 

 series of experiments in these researches, but shall resume the subject. 



From many of his own experiments, and some described by Gautherot, 

 Hisinger, Berzelius, and Ritter, it was apparent that the Voltaic influence was 

 capable not only of decomposing compound bodies, but also of transferring, or, 

 if the term may be permitted, decanting their constituents from one vessel to 

 another. The series of experiments which follows next in order in these re- 

 searches was directed to the examination of the limits of that power, and the 

 effects attending it under conditions not before tried. 



When the substance to be decomposed was insoluble, it was formed into a 

 cup, as in the preceding experiments, and water contained in it was exposed to < 

 the Voltaic action. Thus let A, fig. 5, be aji agate cup, and S a cup made of \ 



Fig. 5. 



