VOL. XLI.] PHILOSOPHICAL TRANSACTIONS. 355 



2. In dry weather, especially in frosty weather, the electricals per se will 

 have their virtue excited with very little action on them; as appears by warming 

 a glass receiver, which, without any rubbing, will cause the threads of a down 

 feather, tied to an upright skewer, to extend themselves as soon as it is put 

 over the feather. Sometimes resin and wax exert their electricity by only being 

 exposed to the open air. 



3. Electricals per se retain the virtue longest when kept near to, or inclosed 

 by, other electricals per se. Thus the rubbed tube will retain its virtue pretty 

 long in dry air, as appears by chasing a feather about the room very long with- 

 out new rubbing ; as also by lumps of resin and sulphur, &c. which have been 

 melted and poured into dry drinking glasses, keeping their virtue long, if kept 

 in those glasses, and wrapped in dry silk, or such sort of paper as will become 

 electrical by rubbing ; for as often as they are exposed to the air, they will 

 attract. 



4. Electrics per se communicate their virtue to any of the non-electrical, 

 when brought near them ; in which case the non- electric attract and repel like 

 the electrics per se. Thus an iron bar suspended by a silken thread, a hair rope, 

 or a dry cat-gut, when an excited electric per se is brought near it, will both 

 attack and send out its effluvia to a non-electric held near it ; as appears in the 

 dark by the light coming out at the end of the bar. 



5. An electric per se loses its excited virtue on communicating to the non- 

 electric ; and the sooner, the more of those bodies are near it. Thus in moist 

 weather the rubbed tube holds its virtue but a little while, because it acts on 

 the moist vapours that float in the air ; and if the rubbed tube be applied to 

 leaf-gold or brass, laid on a stand, it will act on it much longer, and more 

 strongly, than if the same quantity of leaf-gold be laid on a table, which has 

 more non-electric surface than the stand. 



6. When a non-electric is suspended by, or only touches an electric per se, 

 it receives the properties of an electric per se from a rubbed tube or wax, &c. 

 This appears by the fire that flashes from the fingers of a man suspended by 

 hair-ropes, or who stands on a cake of resin, when he has received virtue from 

 the rubbed tube. 



7. The virtue which a non-electric receives from a rubbed tube, runs on to 

 the most distant part of the suspended body, from the place where the tube is 

 applied, and seems to be collected there, from whence it flashes in the dark, 

 snaps, and exerts its attraction on the thread of trial ; though as the virtue 

 runs along, it sometimes shows itself in other parts of the suspended non- 

 electric. 



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