32,6 PHILOSOPHICAL TRANSACTIONS. [aNNO IJOQ. 



the fricated tube to the flame of a candle, to smoke, steam, dust, and to the 

 surfaces of the liquids; but always without any manner of success: which I 

 attribute to the reason before given, of the humid effluvia suddenly condensing 

 on the warm glass; so that the oleaginous quality of the flame and smoke, the 

 moistness of the steam, the smallness of the dust, or the effluvia, of the liquids, 

 would immediately adhere to all parts of the fricated tube, as it was brought 

 within their spheres of activity, preventing the operation of its effluvia, which 

 then seemed to be stopped, or retired within itself; and required a new at- 

 trition to give it vent. 



What next occurred in this experiment was, that on exhausting the air from 

 the tube by the pump, although the like attrition or greater was given it than 

 before, yet very little of the eflfluvium could be discovered, by any motion or 

 disturbance given the leaf-brass, even when held within a quarter of the dis- 

 tance, at which it had been attracted before. After this had been continued 

 for some time, with little success; I say with little success, because, some- 

 times small parts of the leaf-brass, when the tube was held near, and at the 

 same time very warm, would have a motion given them ; but not to be com- 

 pared with what it had, when the experiment ws made without exhausting 

 the air. Besides, I doubt not but some small quantity of air might be left in 

 the tube, and so the attraction might continue in proportion to the quantity of 

 the remaining air. Or the heat produced on the smart attrition of the tube, 

 may, as well in this, as in other experiments, supply the eff^ect and space of 

 such a quantity of air: on re-admitting the air, it was observable, that before 

 any new attrition was given the tube, or was removed from the position and 

 distance it was held at when in vacuo, that several of the forementioned bodies, 

 at rest as to appearance, began suddenly to move, and were some of them at- 

 tracted towards the tube, which, on a fresh attrition, recovered its electrical 

 quality as vigorous as at first. 



When the attrition of the tube was made in the dark, it was very observable, 

 that as the glass became warm, a light would continually follow the motion of 

 the hand, backward and forward; and at the same time, if another hand was 

 held near the tube, a light would be seen to dart from it, with a noise, much 

 like that of a green leaf in the fire, but nothing so loud: though when the 

 experiment has been very silently made, I have heard several cracks, at 7 or 8 

 feet distance, or more; when any thing else, besides the hand, was brought 

 near it, a light would fix upon it, though it touched it not, as I have tried 

 with gold, silver, brass, ivory, wood, &c. giving much the same appearance 

 as the hand. But after the glass came to be exhausted of its air, then on the 

 first attrition, a much larger light ensued, but the quality of giving a light to 



