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cryftals the 12th of November laft, and defired I 
would try whether they afforded the eledric effeds of 
the Tourmalin. They were examined the fame even- 
ing, when I was agreeably furprized to find them, not 
only like Tourmalins in regard to eledric appearances, 
but that the diredion of the eledric fluid moving 
therein, is always along the grain or footings of the 
cryftals ; one end thereof being eledrified plus, and 
the other end minus. And that the fluid is more 
difpofed to pafs in that diredion than in any other, 
may be further colleded from what has been ob- 
ferved upon the grain of the loadftone by Dr. Knight; 
for though the magnetic poles, of a natural loadftone, 
may be varied in any diredion, yet the fame load- 
done does admit of being made much more magne- 
tical along the grain, than acrofs it. 
Now, as feveral of the above gems have different 
eledric poles independent of their fhape, and I have 
not yet been able to vary the diredion of the fluid in 
any one of them, though various methods have been 
tried, and fome of a violent nature; and fince the 
green cryftal, or chryfolite, above defcribed, hath 
likewife the fame eledric poles, but with this dif- 
ference only, that the fluid moves always along the 
flender threads or columns, which is the grain 
thereof, and without differing any change from that 
diredion ; it feems by analogy, that the eledric fluid 
flowing through all of them, moves in that diredion 
in which the grain happens to lie. And the reafon 
appears to be this, that the refiftance the fluid meets 
with in pafling through the gem, is lefs in that di- 
redion, than in any other. 
The 
