568 



Drs. De La Rue and H. W. Miiller. [June 17, 



shunt was also used with the galvanometer, the direction of deviation 

 was found to be to left, which it was desired to know. 



On pressing down e and/, the deviation was to the left and only 

 amounted to 2 divisions. On another occasion, at the same pressure, 

 3,900 cells, current 0*02925 "W., the deviation to the left on pressing 

 down e and / was from 3 to 5 divisions. 



The same tube, with a charge of coal-gas, pressure 3 millims., 

 3,947 M, current 0*01705 W., deflection, on pressing down e and /, 

 7 divisions to left. 



The same tube, with air, pressure 1*5 millims., 1,974 M, current 

 0*02728 W., on pressing down e and /, deviation 20 divisions. The 

 deviation was, therefore, greatest with air ; but if due to a chemical 

 polarisation, it would have been a priori expected to be greatest with 

 coal-gas, which is a mixture of decomposable molecules. The result 

 of the experiments with tube 199 gave the following deviations : — 



Hydrogen. Coal-gas. Air. 



3 7 20 



Again, tube 199, 2,400 cells, pressure 1 millim., 1,316 M, current 

 0*02456 W., deflection on pressing down the keys, 16 to left ; with 

 1,500 cells no discharge, yet a deflection of 10 divisions to the left 

 was produced on pressing down the keys. The deflection in the latter 

 case being clearly due to a static charge. 



Experiments were now made in air with the apparatus (already 

 described *) shown in fig. 5, in order to obtain a vacuum vessel with 

 larger terminals. The terminals are two disks a little over 4 J inches 

 (11 centims.) in diameter, and in the first instance were placed 

 3 inches (7*62 centims.) apart. Pressure 4*5 millims., 5,921 M, 2,400 

 cells, current 0*04366 W., deviation on connecting the disks with the 

 galvanometer, 10 divisions to left. 



With 1,200 cells, no discharge took place, but on connecting the 

 galvanometer a deviation of 27 divisions to the left was, nevertheless, 

 produced. 



At a pressure of 20 millims., 26,316 M, with 3,900 cells, no current 

 passed, but the deviation on connecting the galvanometer, was 66*6 

 divisions to the left. 



The disks were now placed at a distance of 2 inches (5*08 centims.), 

 the pressure being still 20 millims., and the battery 3,900 cells, the 

 discharge now took place, current 0*03896 W., deflection on connecting 

 galvanometer 8*5 to left. 



On reducing the battery to 2,400 cells, the discharge did not take 

 place, but a deviation of 43 divisions was produced on pressing down 

 e and/. 



The disks were placed at 1 inch (2*54 centims.) apart, same pressure,. 

 * "Phil. Trans.," vol. clxxi, p. 75. 



