Obfervations in TLle&ricity. 135 
ing mirror, will produce a fufion of metals, and inftantly 
reduce a number of fubftances prefented to the focus to 
a calx , as the fame effeCt is in many cafes produced 
by a ftroke of lightning; and as the colours of the 
electric and folar light are equally divilible by the prifm; 
may not thefe alfo bear fome kind of relation to each 
other ^? Upon the whole, is there not an high degree 
of probability in the fuppofition, that light, fire, phlo- 
gifton, and electricity, are only different modifications of 
one and the fame principle? See notes 7. 8. and 9. A 
fimilarity in feveral of the phenomena of electricity and 
magnetifm hath been long fince pointed out by Dr. 
price, from M. spinas ; and the effeCt of heat on both 
admirably difplayed by Mr. canton. Of all the fub- 
ftances I have yet examined, the moft difficult to excite, 
I obferved to be a fine, fmooth, unarmed load-ftone, and 
a piece of black lead ; thefe feemed to bid defiance to all 
my rubbers: at length, however, with a piece of new 
flannel they were both excited, in a very fm all degree, 
negatively. In ffiort, I have not yet met with a Angle 
article (on which the experiment could be tried) that I 
could not, with one or other of my rubbers, make in 
(l) Many other particulars might be adduced in this place; but they are pur- 
pofely omitted, this paper being already extended far beyond the limits originally 
intended by the author. 
