28 Mr. J. Brown on tJie Electrification of the 



with the electrometer was employed to test the potential of 

 the gas, after it had passed through the drying-tube, which 

 was bent at the neck to an inclined position, and provided 

 with a paper hood to direct the gas upon the funnel-jets. In 

 the first trial no fog was observed to issue from the tube, and 

 the index moved only about +10 or + 12 divisions. In a 

 second trial some fog issued, and the deflexion was about 

 + 20, afterwards falling to about + 10 while the gas was still 

 forming but no fog visible. 



The experiment was repeated with the calcium chloride 

 replaced by particles, of about the same size, of fine clean 

 gravel. Very little fog appeared, and deflexion was + 60 to 

 + 200. 



In a third modification of the experiment with the drying- 

 tube full of cotton-wool there was a slight issue of fog at first 

 with a deflexion of + 50 ; afterwards less fog and no readable 

 deflexion. 



16. The results of these experiments point towards the 

 conclusion that the electric charge is on the fog particles. 

 But it is to be remembered that if it be on the hydrogen 

 (supposing a gas can be electrified, which appears to be 

 doubtful *) the gas particles might themselves become de- 

 electrified by the processes used to remove the fog, or part 

 with their charges by contact with conductors, or ; indeed, in 

 this way electrify the fog particles themselves. 



The question really is, which was originally electrified — 

 gas or fog ? And in considering this it is to be noted that the 

 fog here dealt with is, as explained in § 12, probably formed 

 at the source of evolution of the gas itself, and therefore its 

 electrification (if it be electrified) may be connected with the 

 kind of chemical or voltaic conditions under which the gas is 

 produced. 



17. As evidence bearing on this latter point, it was suggested 

 to me to try if any electrification would occur during the evo- 

 lution of gas without chemical change from an effervescing 

 liquid such as soda-water. The contents of a freshly-opened 

 bottle were quickly poured into an insulated beaker connected 

 with the electrometer. The effervescence produced no sensible 

 deflexion. If, however, a little dilute alcohol was first placed 

 in the beaker there was a slight positive electrification. 



18. Among a number of miscellaneous experiments made on 

 the subject in general, it may be noted that barium carbonate 

 thrown into dilute sulphuric acid causes strong electrification, 

 while in dilute hydrochloric acid it produces a much weaker 



* See Nahrwold, " Ueber Luftelectricitat," Wied. Ann, xxxi. p. 448, 



