L 445 ] 
tnen declare that you have eftablifhed this, as acon- 
ibnt law, namely, that the Tour malm is always in 
an inver ted flats ; that is, its plus Jide is elefirifed mi- 
nus and the minus Jids plus , whenever either op the tides 
p hotter than the other .* and that it does not return to 
its natural Hate, until the heat is diftributed uniformly 
therein. My experiments on the contrary, you ob- 
its ve, lead one to lay down a rule intirely different, 
viz. That the Tourmalin, when its Jides are une- 
qually heated, exhibits the Jpecies of elefiricity which is 
natural to the hotter fide, that is, the Tourmalin is 
plus on bothfdes , when the plus fide is the hotter 3 and 
tmnus on both Jides , when the minus jide is fo: but that 
it returns to its natural Hate aifo, when the heat is uni- 
formly diftributed. To account for thefe different opi- 
nions, you think it more agreeable to fuppofe fome dif- 
ference in our methods of making the experiments, than 
to queftion the fads I have declared. Accordingly you 
obfeive one cucumfiance which would naturally rive 
rife to fuch a fufpicion. And then tell us, that you 
always placed the Tourmalin upon burning coals, or 
upon a plate of metal, or heated glafs: fo that one 
fide of xhzjlone was always in contact with fome (non 
define) body. That I, on the contrary, in heating 
C’eft die qui me force et m’autorife a declarer, que la reele 
que j ai avancee, eftla feule, qui lui foit conforme. J’ai echaufte 
la Tourmaline de la meme inaniere que Mr. Wilfon, et j’ai pris 
garde, qu elle ne touchat a rien, mais pour le refultat, je l’ai, 
non obftant cela, toujours trouve conforme a ma regie, et tas une 
fade fois a celle de Mr. Wilfon. P 
Je le repete encore ; il m’eft extremement difficile, de fuppofer, 
que Mr. Wilfon foit tombe ici dans une meprife, neanmoins je 
uus convaincu, que de ma part, il n’y a allurement, aucunefaute. 
Ainlije ne fais qu’en juger. 
Vol. LIU. 
M mm 
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