588 Mr. E. F. Burton on the Action of] 



metals in water, in particular to the copper solutions now 

 under consideration. 



Fig. 2. 



Degrees Centigrade 



With each of the salts named in the foregoing section the 

 procedure was the same. Solutions of the salts of deter- 

 mined normality were prepared with the conductivity water, 

 and the amount of such solution added to a given quantity 

 of colloidal solution was measured by counting drops as they 

 came from a fine burette. The tap of the burette was turned 

 so that the liquid dropped at a convenient rate, the number 

 of drops given by 2 ccs. of the liquid was counted, a required 

 number of drops was allowed to fall into the chosen amount 

 of colloidal solution, and finally the number of drops in 

 2 ccs. was counted again with the tap still turned as at 

 the beginning ; the two calibrations always agreed, the 

 burettes giving from 24 to 30 drops per cc. The burettes 

 were always washed with distilled water and, just before 

 being used for any solution, were rinsed with the latter 

 several times. One was thus enabled to introduce into a given 

 amount of colloidal solution a very exact, small quantity of 

 a given electrolytic solution. 



