Electrifications due to the Contact of Gases with Liquids. 57 



negative ought to be set free, and this ought to be easily 

 detected by the electrometer. 



On the whole there appeared, to a strong believer in the 

 theory, a fair and inviting field for experiment. My plan 

 was to examine in the manner indicated instances of the four 

 following types of chemical change : — 



(1) Combination of elements. 



(2) Displacement. 



(3) Double decomposition. 



(4) Change of valency. 



I may as well say at once that from (3) and (4) I got no 

 result whatever, from (1) only an electrification of little 

 importance, and that it was from (2) — instances of displace- 

 ment — that the results I wish to call attention to were obtained. 



The electrometer was made rather sensitive. A high- 

 resistance Daniell through which a current never passed gave 

 a deflexion of 94 divisions either way. An insulated plate on 

 which the reactions were to proceed was fixed so that it could 

 be connected or disconnected at pleasure with the insulated 

 pair of quadrants. The insulation of this plate was tested by 

 giving to it a small charge, and connecting it then with the 

 quadrants. The spot moved and came to rest 200 divisions 

 from zero. It was watched for 3 minutes, during which it 

 maintained its position. 



A porcelain dish containing about 20 c. c. of a strong- 

 solution of potassic iodide was placed on the insulated plate. 

 About the same volume of a strong solution of chlorine in 

 water was placed in a beaker to which was attached a handle 

 of insulating material, and by means of this handle the 

 chlorine water was poured into the potassic iodide. A heavy 

 brown precipitate appeared. The insulated plate was now 

 connected to the insulated quadrants. No deflexion resulted. 

 The experiment was repeated without producing a movement 

 of the spot. 



The porcelain dish was now half filled with distilled water, 

 placed on the insulated stand, and a fragment of potassium 

 cast into it. The usual reaction ensued and the "spot" 

 moved 160 divisions to the left, came to rest, and maintained 

 its position. The quadrants were short-circuited, and the 

 spot returned to within 2 divisions of zero. 



At first view this appeared exactly what I had expected to 

 occur. On reflection, however, many possibilities suggested 

 themselves and each had to be considered. Had I merely 

 detected electricity in the air? May not the deflexion be 

 due to the inductive action of the charged needle on the 



