[ 45 ] 
the Expreffion), as the excited Body from which it 
proceeds. I have found no Body, however denfe, 
whofe Pores are not pervious to Electricity, by a pro- 
per Management, not even Gold itfelf.. 
Proposition II. 
In common with Light., Electricity pervades Glafs, 
but fuffers no Refraction therefrom I having, from 
the mod exact Obfervations, found its Direction to 
be in right Lines, and that through Glaffes of dif- 
ferent Forms, included one within the other, and 
large Spaces left between each Glafs. 
COROLLARV. 
This rectilineal Direction is obfervable only as far 
as the Electricity can penetrate through unexcited 
Originally-electrics, and thofe perfectly dry s nor is 
it at all material, whether thefe Subftances are tranf- 
parent, as Glafs ; femidiaphanous, 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 necelfary that they be Originally- 
electrics. But the Cafe is widely different with re- 
gard to Non-electrics ; wherein the Direction, given, 
to the Electricity by the excited Originally-electric, 
is alter'd as foon as it touches the Surface of a Non- 
electric, and is propagated with a Degree of Swift- 
nefs fcarcely to be meafured in all poffible Directions, 
to impregnate the whole Non-electric Mate in Con- 
tact with it, or nearly fo, however different in itfelf 
and which mud of Neceflity be terminated by an 
Originally- 
