1897.] and the formation of Clouds in Charged Gases. 247 



insulated quadrants of the electrometer, the generating apparatus 

 G being connected to earth. These connections can be easily 

 made by means of the mercury cups in the paraffin block P. The 

 spot of light on the electrometer scale shows a large deflection 

 in the positive direction as the hydrogen enters /. If G be 

 now removed and the hydrogen left in / for the space of five or 

 ten minutes it will be found that if it be then displaced by 

 blowing in unelectrified air that the spot of light will return 

 almost to the place from which it started showing that the gas 

 retained more than 95 per cent, of its original charge. Other 

 experiments similar to this showed that when a gas is left in an 

 inductor for the space of two hours that it still retains from ith 

 to ^th of its original charge. 



6. With regard to the fact that the hydrogen, given off 

 when iron is dissolving in sulphuric acid, carries with it a positive 

 charge, I find that this result had previously been obtained by 

 Enright, who examined the electrical properties of several newly 

 prepared gases, and although his investigations were incomplete, 

 and his results capable of different interpretations, nevertheless 

 they have not been accorded the credit they deserve. None of his 

 experiments were directed to finding out whether the charge was 

 on the gas or on the spray, but he unhesitatingly assumed that 

 the electricity was in all cases carried by the gas. Under these 

 circumstances it is easy to see that some of his conclusions may 

 have been erroneous. (Enright : 'Electromotive force of contact 

 between a liquid and a gas,' Phil. Mag. 1890; Nature, vol. 36.) 



Enright's experiments were repeated by Brown (Brown : 

 ' Electrification of the Effluvia from Chemical or from Voltaic 

 Reactions'), who found that all the experimental results were 

 quite correct. No new light was thrown on the matter ; the 

 conclusion which the experimenter himself arrived at was that it 

 was impossible to decide whether the gas or " effluvium," which it 

 carries with it from the acid in which a metal is dissolving, is 

 charged, the balance of evidence being in favour of the latter. 

 Professor Lodge (Phil. Mag. 1890; Nature, vol. 36) attributed the 

 cause of the electrification which Enright observed to the well- 

 known electrification of spray, but the following experiment will 

 show that his interpretation was wrong. 



7. The experiment which Enright performed and from which 

 he drew his conclusions with regard to a metal dissolving in an 

 acid is very easily performed by insulating the apparatus G, fig. 1, 

 and connecting it to the quadrants of the electrometer. If the 

 vessel A be left open so that the hydrogen may escape directly 

 into the air it will be found that when a 50 per cent, solution of 



