554 PHILOSOPHICAL TRANSACTIONS. [aNNO 1774. 



placed my own electrometer in its stand, on the prime-conductor, fig, 4 ; and 

 having taken off a spark or two, as before ; I again worked the machine, to 

 observe the repellency of the index from the stem ; and found it constantly to 

 vibrate between 5 and 10 degrees of the quadrant, which was divided into 15. 

 I then brought the smoking taper within 4 or 5 inches of the back of the 

 rubber, as before ; and observed, that on the attraction of the smoke to it, the 

 index presently began to rise, and in a very short time got up to right angles. 

 I repeated the experiment several times, with the same success. I then tried the 

 experiment by bringing my finger to the same distance from the rubber, and 

 pointing towards it ; but this, in many trials, had not the least effect. The 

 taper likewise, when held at the same distance, and not smoking, had no effect 

 at all. I am convinced therefore, that the smoke was the medium which con 

 veyed the electricity from my hand to the insulated rubber. 



Exper. 6. I placed on a stand, on the prime-conductor, a piece of smoking 

 wax taper, fig. 5, when immediately on working the machine, the smoke, from 

 a large and diffused volume, was much contracted, and its motion upwards 

 greatly accelerated. I then took off the electricity of the conductor, and held a 

 pair of cork balls a quarter of an inch diameter, hung on threads 2\ inches 

 long, perpendicularly over the rising smoke ; and as high as I could possibly 

 reach, standing on a chair ; this might raise the balls about 5-^ feet above th 

 prime-conductor ; when, working the machine, in a few seconds the balls 

 separated to half an inch distance. I then removed the taper, but could not 

 perceive that the balls were at all affected without it ; but on replacing it, they 

 separated as before. I repeated the experiment several times, with and without 

 the taper, and the different effect was constantly as above recited. I then set a 

 tin saucer on the stand, and placed on the saucer a half pint mug of boiling 

 water, fig. 6 ; and over this water I presented the balls in the rising vapour ; as 

 had before been done in the smoke. On working the machine a kv/ seconds, 

 the balls diverged to the distance of the 12th part of an inch. On removing the 

 water, and presenting the balls as before, they never separated at all, though I 

 worked the machine for a longer time ; but on replacing the water, in a few 

 seconds the balls diverged as at first. These experiments I repeated several 

 times, and always with the same success. The smoke therefore, in the first ex- 

 periment, and the vapour of the hot water in this last, was certainly the medium 

 which conveyed the electricity from the prime conductor to the balls : and I 

 think I may now very safely pronounce, that smoke, and the vapour of hot 

 water, are absolutely conductors of electricity ; though smoke is a far better one 

 than the vapour of hot water, and both of them are exceedingly bad ones. 

 § 2. Of the Direction of the Electric Matter, in the Discharge of the Ley den 



Bottle. 



Exper. 1 . Light a snaall wax taper, and place it, with the flame exactly be- 



