60 Mr. J. Enright on Electrifications due 



sign to the charge produced by the action of zinc and hydro- 

 chloric acid, it was certain that the latter was not dne to any 

 atmospheric cause. But a new point of great importance 

 had arisen. Whence came the positive charge in the air 

 near the instrument ? The idea of its being due to the 

 evolved hvdrogen at once suggested itself. For some time 

 before testing with the sponge, I had been repeating the 

 experiment with zinc and hydrochloric acid in order to satisfy 

 myself as to its constancy, and a considerable quantity of 

 hydrogen had escaped into the air. 



The charge on the evolved hydrogen opposite in sign to 

 that on the insulated generator ! If this were really the case 

 I saw that I should have to give up certain ideas which I had 

 been fostering while dealing with these experiments. The 

 point had to be at once cleared up. 



A zinc goblet was metallically attached, mouth downwards, 

 to the insulated plate. A long-necked flask containing zinc 

 and hydrochloric acid was placed underneath in such position 

 that the hydrogen found its way into the inverted goblet. 

 In two minutes after so placing the hydrogen generator the 

 goblet was tested by connecting it with the insulated quad- 

 rants. The spot moved 78 divisions to the right, indicating 

 that the hydrogen escaped with a positive charge — that is to 

 say, as already suspected, its charge was opposite in sign to 

 the acid and generator from which it was evolved. 



The experiment was several times repeated, and always 

 with the same result, but it was noticeable that the positive 

 charge on the hydrogen was much less in quantity than the 

 negative charge on the generator. If they were in reality 

 oppositely charged, the quantities, as in all such cases, would 

 be exactly equal. I urged, in explanation, that the hydrogen 

 moving over the moist glass of the long-necked generator 

 must lose some of its charge. However, a confirmatory ex- 

 periment was devised. 



A second insulated plate was set up and connected metal- 

 lically with the first. A hydrogen generator, containing zinc 

 and hydrochloric acid, was placed on one, and a suitable pneu- 

 matic trough was placed on the other, in such manner that 

 the gas might be generated and collected on the insulated 

 plates, which were connected to the insulated quadrants. A 

 stream of hydrogen was allowed to pass, and by means of an 

 insulating rod the delivery-tube could be placed so that the 

 hydrogen might get into the air or be collected and retained 

 on the insulated plates at pleasure. It was found that as long- 

 as the gas did not escape the spot remained motionless, but 

 that when it escaped from the plates into the air the spot 



