to the Contact of Gases ivith Liquids. 59 



sulphuric acid, sodium and nitric acid, and many other such 

 combinations were tried, and eventually I found that sodium 

 and strong acetic acid gave an invariable result, viz., a 

 positive charge on the dish in which the reaction took place. 

 This has not tailed hitherto in a single instance. 



I reviewed the state of affairs. The first thing to do, as it 

 appeared to me, was to ascertain whether or not the hydrogen 

 carried a charge, and, if so, to determine its sign. I found it 

 so difficult to work with sodium that after many unsatisfactory 

 attempts I decided to search for another metal which would 

 give a similar constant and definite result. One naturally 

 turned to zinc. 



A piece of zinc was thrown into dilute sulphuric acid 

 which was put into the insulated dish, the connexions being 

 as already described. The spot rapidly moved 36 divisions 

 to the left, turned, went back- across zero and up on the other 

 side 120 divisions. This was not encouraging. It seemed 

 to be the beginning of another set of irregular deflexions. 

 It, however, went to show that electrification was an accom- 

 paniment of most chemical reactions. I repeated the experi- 

 ment several times, varying the degree of dilution of the acid, 

 but failed then to get constant results. I next tried hydro- 

 chloric acid. 



A small portion was placed in the insulated dish and a 

 particle of zinc thrown into it. The spot rapidly moved off 

 the scale to the left, indicating a negative charge on the dish. 

 The quadrants were short-circuited, and the spot returned 

 to zero. Repetition was followed by the same result, and 

 fortunately this turned out to be as constant a deflexion to 

 the left as that from sodium and acetic acid was to the right, 

 while it was much greater in quantity. 



I now concentrated my attention on zinc and hydrochloric 

 acid. In this experiment, as in all others where a gas escaped 

 into the air, it was possible, though not likely, that the resulting 

 deflexions were due to atmospheric electricity, and I thought 

 it as well to settle this point at Once. A piece of sponge was 

 saturated with alcohol and placed on the insulated plates. It 

 was then fired, and burned with a large flame. The insulated 

 plate was connected to the quadrants when the sponge ceased 

 to burn, and the spot at once moved 10 divisions to the right, 

 indicating a small positive charge on the plate. The experi- 

 ment was repeated in every particular except the burning of 

 the sponge, but with the result of only a disturbance of the 

 spot of a few divisions. 



The air in the neighbourhood of the insulated plate 

 appeared to be slightly electrified, but as it was of opposite 



