OHAP. II. DIFFEBENTIAL CUEEENTS. 1 7 



muriates, &c. It was negative with sulphuric and 

 phosphoric acids. 



Phosphoric acid was positive with muriatic, sul- 

 phuric, nitric acids; the dlkaline and saline 

 solutions. 



Water in combining with an acid acts as an 

 alkali ; with alkalies as an acid. 



With neutral solutions, the most saturated acted 

 as an acid to the less saturated. Becqueeel con- 

 siders, that in the reaction of one solution upon 

 another, that which performs the part of an acid 

 takes positive, that of an alkali negative electricity. 

 The effect, it may be observed, that is produced 

 under these circumstances upon the galvanometer 

 is nothing like so great as that which occurs with 

 the voltaic circle, where metals are employed. 



Before quitting the subject of the developement of 

 electricity during chemical action, I shall take the 

 opportunity of speaking of what are called differential 

 currents and combined currents. If we take a vessel 

 or glass cell and divide it into three compartments 

 by a membrane, so as to form three distinct cells, 

 and into the extreme compartments pour a solution 

 of potash, and into the centre one nitric acid, then 

 place the platinum electrodes of a galvanometer 

 into the potash cells, no effect wiU occur upon the 

 needle, provided the arrangement be perfect; but 

 if one of the electrodes be placed in the acid, and 

 the other in the alkali, we then have the ordinary 

 result. In the former instance the currents pro- 

 c 



