1884.] Chemical Corrosion and Voltaic Current. 331 



below the centre of suspension. This needle is placed, with its one 

 effective pole in the axial line of the balance, level with the centre of 

 the compensator. 



The balance, with the modifications described, is represented in 

 fig. 4. 



February 21, 1884. 



THE PRESIDENT in the Chair. 



The Presents received were laid on the table, and thanks ordered 

 for them. 



The following Papers were read : — 



I. " On some Relations of Chemical Corrosion to Voltaic Cur- 

 rent." By G. Gore, F.R.S., LL.D. Received February 11, 

 1884. 



The chief object of this research was to ascertain the amounts of 

 voltaic current produced by the chemical corrosion of known weights 

 of various metals in different liquids. The research was also made to 

 throw light upon the conditions which determine the entire conver- 

 sion of potential molecular energy into external (i.e., available) 

 electric current. The method adopted was to take about six or eight 

 ounces by measure of a corrosive electrolyte and divide it into two 

 equal volumes in two similar glass vessels. Two pieces of metal of 

 equal dimensions were then cut from the same sheet, cleaned perfectly, 

 and weighed. One of the pieces was employed as the positive plate 

 of a voltaic cell in one of the portions of liquid, and the other as a 

 comparison corrosion sheet in the other portion. The negative metal 

 of the voltaic cell was in nearly all cases a large cylinder of sheet 

 platinum, and surrounded the positive one. The positive and 

 comparison plates were wholly immersed in the separate portions of 

 liquid, except that the former had a narrow exterior projecting strip 

 for connexion in a circuit. The current from the cell was passed by 

 means of a small sheet silver anode (-J inch by f inch), and a smaller 

 silver cathode (J inch by f inch) in a third vessel, through a 

 cyanide of silver plating solution containing the least practicable 

 proportion of free potassic cyanide in order to obtain the maximum 

 amount of silver deposit. 



During each experiment observations were made of any liberation 



