1895.] Electrification of Air, <J-c., ly bubbling through Water. 345 



29. The blowing of oxygen from a cylinder, obtained from the 

 Oxygen Company, through water, gave as a mean of four experiments, 

 a positive electrification to the water of half a volt in 10 minutes. 

 When continued for 55 minutes, it gave the very decided result of 

 5 volts positive. 



30. Hydrogen prepared from zinc and dilute sulphuric acid was 

 passed into a large metal gas-holder ; and was passed on from this to 

 bubble through the water in the insulated jar. In two experiments 

 this was done immediately after the preparation of the hydrogen ; in 

 another it was done after the hydrogen had remained 18 hours in the 

 gas-holder. In each of the three experiments the water was electrified 

 to 2 volts positive in 10 minutes. 



When the hydrogen was allowed to pass direct through a tube 

 from the Wolff e's bottle where it was generated, to bubble in the in- 

 sulated jar, the magnitude of the effect obtained was very much 

 larger. In one case a mixture of muriatic acid and sulphuric acid 

 arid water was used, and the reading went off the scale positive in 

 30 seconds (more than 10 volts). In other two experiments, with dilute 

 sulphuric acid and zinc in the Wolffe's bottle, the electrifications 

 obtained were 6 volts positive in 7 minutes, and 7'3 volts positive 

 in 13 minutes, in the last of which the hydrogen was allowed to 

 bubble through caustic potash contained in a small bottle between 

 the Wolffe's bottle and the insulated jar. 



The hydrogen was next generated in the insulated jar itself, the 

 tube for ingress of air used in the ordinary experiments being taken 

 away. 200 c.c. of pure water, along with some granulated zinc, was 

 put into the jar. Then some pure sulphuric acid was added, and 

 electrometer readings were taken. In two experiments with no 

 screen in the jar ( 16) the reading went off the scale negative (1) 

 in 2 minutes and (2) in 4 minutes (more than 9 volts in each case). 

 In another experiment, in other respects the same, but with a copper 

 screen 7 cm. above the surface of the liquid, the electrification 

 showed 2 volts negative in 2 minutes, then came back to zero in 

 5 minutes, and in the next 6 minutes went 4 volts positive. The jar 

 and pair of quadrants connected with it were then metallically con- 

 nected with the outer case of the electrometer for a few seconds, and 

 reinsulated ; in 5 minutes the reading went up to 2 volts positive. A 

 little more sulphuric acid was added to the jar, which was disinsu- 

 lated for a short time and reinsulated ; the reading went up to 

 7 volts positive in 4 minutes. The jar was again disinsulated for a 

 few seconds and reinsulated; the reading went up in 4| minutes to 

 6^r volts positive. 



31. Coal-gas, bubbled through water in the insulated jar, gave 

 1'4 volts positive in 10 minutes. 



32. In the ordinary experiment of bubbling air through a small 



