[ '4i ] 



Having, on the contrary, obferved that bodies, 

 infulated with dried filk, had loft their electricity in 

 a very fhort time, I attempted to render it a non- 

 conductor, by having varnimed it over with oil of 

 turpentine, balfam of fulphur, and fuch like, but 

 did not fucceed ; for filks fo treated foon became a 

 conductor, and increafed considerably in weight, if 

 the air happened not to be very * dry - y fo much 

 indeed, that I think ordinary (ilk, from its power of 

 abforbing moifture from the air, may well ferve as 

 an occafional hygrometer, either by being put into 

 a balance, or by having an electrified body infulated 

 with it. 



When the denfity of fogs, floating near the earth, 

 increafes confiderably, the balls always approach ; 

 but when they are lituated high in air, the reverfe 

 generally happens. I had an opportunity of remark- 

 ing a ftruggle between breezes from the north-weft 

 and fouth-eaft at the fame time, in which the one , 

 feemed fometimes to prevail, and afterwards the 

 other. This contention was fucceeded by a fmoaky 

 hazinefs, which, like a fog, occafioned the balls to 

 open : as the hazinefs -f* thickened, they opened 



* Even glafs attracts rrioifture to its Surface, which makes it 

 a conductor of electricity, and, confequently, not fo convenient 

 as fealing-wax. 



f An electrical body, when contracted in its dimenfion, will 

 have its electricity increafed, as appears by Dr. Franklin's cu- 

 rious experiment with the chain and filver can.. I alio have dif- 

 covered, from repeated trials, that a piece of flannel, filk, &c. 

 excited, and fuddenly twilled, not only ftruck at a greater di- 

 ftance than before, but fometimes emitted pencils of fire into the 

 air. May we not hence infer why the electricity of vapour, &c. 

 (when not in contact with the earth) increafes by condenfa- 

 tion ? 



wider, 



