1883.] Electric Discharge with Chloride of Silver Battery. # 295 



(fig. 6) ; this was re-occluded by standing for a couple of days, leaving the 

 tube free, and again given off to form a new mirror-like coating with 

 a fresh discharge; this property has continued since March, 1875. 



Fig. 5. 



Fig. 6. 



/ 



The paper next describes experiments to ascertain the length of the 

 spark in dry air and in air saturated with moisture. It was found to 

 be practically the same in both cases. With 10,860 cells the mean 

 length of the spark between two paraboloidal points was found to be 

 in dry air 0"45 inch (1*1 centims.), in moist air 0'M7 inch (1"1 

 centims.). 



The next subject taken up is the discharge in a tube from two 

 batteries, first in the same, and then in contrary directions. In the 

 tube are two terminals at each end, one pair at opposite ends being 

 enclosed in two short pieces of tube, 9 inches (22'8 centims.) long, 

 and \ inch (1*27 centims.) diameter ; the main tube being 31 inches 

 (95*2 centims.) long and If inches (4*4 centims.) diameter (fig. 7). 

 The various phases of the stratified discharge are represented in an 

 engraved mezzotint steel plate copied from photographs, and show 

 the effect of the one stratified discharge on another stratified dis- 

 charge produced by a second battery. It is seen that two discharges 

 in contrary directions may take place in the same tube, and that the 

 one modifies the aspect of the other. 



Experiments are also described in a tube in the form of a cross 

 with four arms at right angles (fig. 8) ; with two separate batteries 

 connected in various ways with the different members. The experi- 

 ments were made both in air and in hydrogen. By the introduction 

 of external resistance in one of the batteries, the discharge could be 

 readily identified as belonging to that battery by the effect of the 

 resistance on the character of the stratification. In one of the mezzo- 

 tint plates are several figures copied from photographs which show 

 clearly the phenomena produced. Calling the poles P and N", of one 

 battery, A, and P' and N' of the other, B, it is shown in one case 

 when two currents were equal 0'0083 ampere, that a discharge from 

 A battery goes from P in the direction of N only so far as the 

 junction at the cross and then turns off to N', the negative of the 



