VOL. XLIV,]) PHILOSOPHICAL TRANSACTIONS, 1Q7 



other conception of its manner of acting than as rays from a centre, which indeed 

 is confirmed by several experiments. 



Prop. 1. — In common with light, electricity pervades glass, but suffers no re- 

 fraction from it; he having, from the most exact observations, found its direction 

 to be in right lines, and that through glasses of different forms, included one 

 within the other, and large spaces left between each glass. 



Carol. — This rectilineal direction is observable only as fai* as the electricity can 

 penetrate through unexcited originally-electrics, and those perfectly dry; nor is 

 it at all material, whether these substances are transparent, as glass; semidiaphan- 

 ous, as porcelain, or thin cakes of white wax; or quite opaque, as thick woollen 

 cloth, as well as woven silk of various colours; it is only necessary that they be 

 originally-electrics. But the case is widely different with regard to non-electrics; 

 wherein the direction, given to the electricity by the excited originally-electric, is 

 altered as soon as it touches the surface of a non-electric, and is propagated with a 

 degree of swiftness, scarcely to be measured, in all possible directions, to impreg- 

 nate the whole non-electric mass in contact with it, or nearly so, however differ 

 ent in itself; and which must of necessity be terminated by an originally-electric, 

 before the electricity exerts the least attraction; and then this power is observed 

 first at that part of the non-electric the most remote from the originally-electric. 

 Thus, for example, by an excited tube held over it, leaf-gold will be attracted 

 through glass, cloth, &c. held horizontally in the hand of a man standing on the 

 floor; and this attraction is exerted to a considerable distance. On the contrary, 

 the rubbed tube will not attract leaf-gold, or other light bodies, however near, 

 through silver, tin, the thinnest board, paper, or any other non-electric, held in 

 the manner beforementioned. 



Prop. 3. — Electricity, in common with light likewise, when its forces are col- 

 lected, and a proper direction given to it, on a proper object, produces fire and 

 flame. 



Corol. — ^The fire of electricity, as before observed, is extremely delicate ; and 

 sets on fire, as far as yet experienced, only inflammable vapours. Nor is this 

 flame at all heightened, by being superinduced on an iron rod, red-hot with 

 coarser culinary fire, as in a preceding experiment; nor diminiehed by being 

 directed on cold water. However, being desirous of knowing if this flame woiJd 

 be affected by a still greater degree of cold, Mr. W. made an artificial cold ; by 

 which the mercury, in a very nice thermometer adjusted to Fahrenheit's scale, 

 was depressed in about 4 minutes, from 1 5 degrees above the freezing point ta 

 30 degrees below it; that is, the mercury fell 45 degrees. From this cold mix- 

 ture, when electrified, the flashes were as powerful, and the stroke as smart, as. 

 from the red-hot iron. 



