356 



GALVANISM. 



menced, the presence of soda in a free state was manifested in the cup N, and 

 muriatic aud in the cup P. The muriatic acid drawn from the cup N, through | 

 the litmus paper, was seen to form a dense precipitate in the cup I, and the t 

 soda passing through the turmeric paper from the cup P was observed in the 

 cup I, forming a more diffused and lighter precipitate. But neither the acid in 

 passing through the litmus paper, nor the alkali in passing through the turmeric 

 paper, produced any change in the color of these tests. 



When salts having metallic oxides as bases were placed in the cup P, acid 

 solutions being put in I, the oxides passed through the acids ; but their prog- 

 ress was much slower than that of the alkalies. When a solution of the green 

 sulphate of iron was placed in P, and muriatic acid in I, the green oxide of 

 iron began to appear in about ten hours on the amianthus connecting N and I ; 

 and it took three days to collect any considerable quantity of it in the cup N. 

 The results were similar when solutions of sulphate of copper, nitrate of lead, 

 and nitro-muriate of tin, were placed in the cup P. 



The transmission of the constituents of salts through solutions of the neutral 

 salts was next tried, and the results were what was anticipated. Saline solu- 

 tions being placed in N and I, and purified water in P, the alkali of I first 

 began to pass into N : then the alkali of P, after passing through I, reached 

 N, and at the same time the acid of I passed into P. Ultimately the two acids 

 were collected in P, and the two alkalies in N. As an example of this, the 

 cup N was filled with a solution of the muriate of baryta, the cup I with sul- 

 phate of potash, and the cup P with pure water. A battery of 150 pairs 

 brought sulphuric acid in five minutes, and muriatic acid in two hours, into P. 



When the cup P was filled with a solution of sulphate of potash, I with mu- 

 riate of baryta, and N with distilled water, the baryta appeared in the water in 

 a few minutes ; after an hour, the potash became sensible in it. 



When the muriate of baryta was in P, the sulphate of potash in I, and water 

 in N, the potash soon appeared in the water ; but the baryta was arrested in 

 the intermediate cup by the sulphuric acid, and sulphate of baryta was abun- 

 dantly precipitated. In like manner, when sulphate of silver was placed in 

 the cup I, muriate of baryta being in N, and water in P, sulphuric acid alone 

 passed into P, and a precipitation took place in I. 



The effects of the electric current on the principles of vegetable and animal 

 substances was next tried. The fresh stalk of a polyanthus-leaf was used in- 

 stead of the siphon of amianthus, to connect the two cups P and N (fig. 7), the 



Fig. 7. 



cup I being omitted. The cup P was filled with a solution of nitrate of stron- 

 tia, and the cup N with purified water. The water soon became green, and 

 showed the presence of alkali ; and the solution in the cup P indicated the 

 presence of free nitric acid. After ten minutes, the alkaline matter in N being 



