Electricity of Drops, 349 



produced much smaller effects. The effect of adding a small 

 quantity of rosaniline to water could be detected by the 

 alteration produced in the deflexion of the electrometer before 

 any colour was appreciable. 



Fluorescene and eosine produce very marked effects, but of 

 the opposite kind to those due to methyl violet and rosaniline, 

 i. e., instead of reversing- the water effect, they increase it. Thus 

 when water gave a deflexion 280 + , a weak solution of fluores- 

 cene gave a deflexion 700+ ; and when water gave a deflexion 

 200 + , a weak solution of eosine gave a deflexion 370 + . 

 As the solutions of eosine and fluorescene increase in strength 

 the electrical effects get smaller, until with very strong 

 solutions a small negative deflexion is obtained in both cases. 



When a solution has become electrically neutral, ?'. <?. when 

 the drops do not produce any deflexion of the electrometer, 

 the addition of other reagents seems to produce very little 

 effect. Thus to 100 c. c. of a neutral eosine solution I added 

 12 drops of a rosaniline solution, and the solution still re- 

 mained neutral, though the addition of the same quantity of 

 the rosaniline solution to 100 c. c. of distilled water produced 

 a change in the deflexion of the electrometer of 400 scale- 

 divisions. 



The effect produced by any reagent depends to a very large 

 extent on the solvent in which it is dissolved. I tried the 

 effect of dissolving rosaniline, methyl violet, fluorescene, 

 eosine, and phenol in absolute alcohol as well as in methylated 

 spirit : the electrical effects, however, were small, in no way 

 comparable to the enormous effects produced by these sub- 

 stances when dissolved in water. 



Isomeric Substances. 



Dr. Ruhemann was kind enough to supply me with samples 

 of the three isomeric substances hydroquinone, pyrocatechin, 

 and resorcin. The solutions of these were of the same strength, 

 •5 gramme of the salt being dissolved in a litre of water. The 

 results were as follows : — 



Substance. Deflexion. 



Water 210 + 



Pyrocatechin 205 + 



Kesorcin 205-}- 



Hydroquinone 255 + 



Thus the hydroquinone is the only one of the three which 

 produces any appreciable effect on the electricity produced by 

 the drops. 



