ELECTRO-CHEMISTRY. 1 7 



water, the water in I being tinged with a solution of 

 litmus, how is it that, in the decomposition of the 

 sulphate of potash, the acid base of the salt is trans- 

 ferred to cup P, but in passing through the interme- 

 diate cup I the blue tincture of litmus does not 

 assume a red colour ? 



The constituents of a neutral salt possess neither 

 the properties of an acid nor those of an alkali ; 

 when, therefore, the sulphate of potash in the cup N 

 is decomposed, the acid base of the salt has not yet 

 acquired the properties of an acid it has not yet 

 combined with positive electricity ; it therefore passes 

 through the solution of litmus in the intermediate 

 cup I, without changing its blue colour into red ; and 

 is decanted into cup P, where it combines with posi- 

 tive electricity, and has its acid properties restored. 

 If the contents of the cup P be now poured into the 

 intermediate cup I, the blue tincture of the litmus 

 will assume a red colour. 



19. When the cup P is filled with a solution of 

 the sulphate of potash, and the cups N and I with 

 distilled water, the water in I being tinged with 

 turmeric, how is it that in the decomposition of the 

 sulphate of potash, the alkaline base of the salt, in 

 passing through the intermediate cup I on its route 

 to N, does not change the colour of the turmeric ? 



c 



