ELECTRO-CHEMISTRY. 21 



city with which it is united, the baryta is decom- 

 posed, the negative electricity is set free, and the 

 base of the acid is arrested in the intermediate cup 

 I by combining with the base of baryta, and because 

 of this a precipitate of the sulphate of baryta takes 

 place. 



23. When an acid and an alkali are brought into 

 contact, how is it that great heat is evolved and a 

 compound formed, possessing neither the properties 

 of an acid nor an alkali ? 



The acid, in combining with an alkali, gives off 

 its positive electricity, and is thus deprived of that 

 which imparted to it the properties of an acid ; and 

 the alkali, in combining with an acid, gives off its 

 negative electricity, and is thus deprived of that 

 which imparted to it alkaline properties ; and be- 

 cause of this a compound is formed by the combina- 

 tion of the ponderable constituents of the acid and 

 alkali possessing neither alkaline properties nor 

 those of an acid, and the great heat evolved is con- 

 sequent upon the union of the two electricities which 

 are given off. 



24. If a platinum capsule, which contains a solu- 

 tion of caustic potash, be connected w r ith one wire 

 of an electrometer, and a slip of platinum connected 

 with the other wire is dipped into nitric acid, and 



