94 



Dr. G. Gore. 



made experiments with a series of different capillary electroscopes in a 

 horizontal position, taking care to remove an additional part of the 

 apparatus in each successive experiment : — 



The first electroscope (No- 1) consisted of two similar capillary 

 tubes, inserted in two pressure- chambers, connected together in a 

 direct line by a long straight glass tube of narrow bore, each chamber 

 being provided with a platinum wire terminal. The chambers, con- 

 necting tube, and capillaries were filled with mercury ; air was ex- 

 cluded, and the ends of the capillaries were immersed as usual in 

 dilute sulphuric acid containing electrodes of mercury. In the second 

 apparatus (No. 2) the intermediate glass tube was removed, and a 

 •single pressure-chamber, 60 centims. in length (with a platinum wire 

 at each end), was used in its stead. In a third (No. 3), the chamber 

 was reduced to a length of about 8 centims., and had a platinum wire 

 at each end. In a fourth (No. 4), the chamber was removed altogether, 

 and the central tube and capillaries were formed of a single piece of 

 glass, the middle part being about 4 centims. long, of the usual 

 diameter and bore, and having a fine wire of platinum sealed into it as 

 an electrode. 



I also made experiments with a series of electroscopes in a vertical 

 position, each successive apparatus being increasingly simple, and 

 each closed at the upper end and perfectly filled with mercury, except 

 the lower end containing the electrolyte. 



The first (No. la) consisted of the capillary (dipping as usual into 

 dilute sulphuric acid with a mercury electrode), short pressure- cham- 

 ber, and a long glass tube above it, closed at the top by a thick india- 

 rubber tube and a strong pressure-clip. In the second (No. 2a), the 

 long glass tube was dispensed with, and the upper end of the pressure- 

 chamber was closed by a glass plug. In the third (No. 3a), the 

 chamber was excluded, the platinum wire electrode being melted into 

 the side of the large part of the glass tube, and the upper end of that 

 tube drawn out to a fine point, and closed by melting sealing-wax 

 whilst mercury was exuding from it. The fourth (No. 4<x) was 

 similar to the third, except that the upper end was closed by fusing a 

 part of the fine tube itself whilst it was filled with mercury. And in 

 a fifth (No. ha), the bulky portion of the glass tube was dispensed 

 with by fixing an extremely fine platinum wire in the somewhat 

 larger and upper part of the capillary by fusion. 



In all the experiments made with these different instruments, 

 whether horizontal or vertical, the electrolyte used was a mixture of 

 1 volume of pure sulphuric acid and 14 of water, and the voltaic 

 current employed was that already mentioned (see p. 86). In each of 

 the experiments with them the mercury moved in the same direction 

 as the current, whether that was towards the point of the capillary 

 tube or the reverse. In many of the experiments a charge from an 



