feCt date, and remains fo near a quarter of an hour : 
after that time the fhocks gradually decreafe as the 
done grows cooler, till at lad they quite ceafe, and 
it returns to its conducting date again : but this date 
appears before the done is quite cold. 
Experiments of this kind fucceed in all bodies 
abounding in calx or earth, as dones, dried clay, 
wood when rotten or burnt in the dre till the furface 
becomes black. 
Among other fubdances, I tried a common tobacco- 
pipe, part of which near the middle I heated to a 
proper degree, and then applied one end of it to the 
electrified bar, while the other was held in the hand ; 
and I obferved that the eleCtric duid pafled no farther 
along the pipe than to the heated part. 
To thefe changes brought about with fudden vio- 
lence, I mud add the univerfal change going on in 
all animal and vegetable folids, as they are growing 
dry. Not only their adies redd the padage of the 
eleCtric fluid, but they of themfelves arrive at this 
date while yet hard and intire 5 and that much fooner 
than one would imagine ; for I have bones and hard 
wood that perfectly redd the padage, tho’ yet ca- 
pable of yielding a bright flame, but fcarce a vidble 
lmoke : fo that beddes an evaporation of their 
moidure, but a partial progrefs can have been made 
in the dilcharge of their fulphur. 
I fubmit to your judgment, how much this con- 
vertibility may contribute to a farther knowlege of 
the laws of eleCtricity. I am. Sir, 
Old Palace- Yard, 
March 15, 1759. 
Your mod humble Servant, 
Edward Delaval. 
XIV. An 
