Passage of Electricity through Liquids, 



263 



elements from each other is here of very great influence ; yet we 

 cannot calculate on getting results accurate to 5 per cent, with 

 positive or negative electricity, unless the battery be set up with 

 freshly amalgamated zinc and platinum plates^ with concentrated 

 nitric acid and dilute sulphuric acid of 1*.2 specific gravity, and 

 the cylinders have lain for several days in just such sulphuric 

 acid. I could not bring the accuracy of the observations nearer 

 than 2 per cent, of the entire value^ except when I took the 

 mean of a great many experiments, while Kohlrausch attained an 

 accuracy of 1 per cent. Kohlrausch, indeed, like other observers, 

 met with greater differences in the tensions of the free electricity 

 of the two poles than I have given; bat he used elements which 

 were filled with badly conducting liquids. But the liquids in 

 my Grovels battery were the best conductors known (apart from 

 metallic mercury) ; and hence it was extremely surprising, not- 

 withstanding this, to find differences in the tension of the free 

 electricity of the two poles (compare § 61). Of course this dif- 

 ference of the two poles is met with in the closed as well as in 

 the open circuit. 



The following Table gives under 4-e and — <? the quantity of 

 positive or negative electricity of the condenser-plate when the 

 platinum plates in the glass trough were at the distance / in the 

 first column, where / therefore represents the length of the co- 

 lumn of water traversed by the current. Between the separate 

 determinations with the closed circuit, determinations were made 

 with the open circuit, in order to control the constancy of the 

 electromotive force. The mean of all these experiments is given 

 opposite to /=co . 



Column of water 60*6 millims. in breadth_5 63-5 millims. in 



height. 



I. 



+e. 



— e. 



Mean. 



CO 



11-251 



-11125 



11-19 



400 



11-2G 



-11-23 



11-24 



200 



11-30 



-11-26 



11-28 



100 



10-84 



-11-30 



11-07 



50 



11-01 



-IISO 



11-17 



20 



11-30 



-11-19 



11-21 



10 



1133 



-11-23 



11-28 



Temperature = 14°'6 



According to theory, the quantity of electricity which collects 

 upon the condenser-plate is proportional to the difference of po- 

 tentials (tensions) of the free electricity at those places of the 



