[ 33 8 ] 
this letter, our author endeavours to eftablifh his 
opinion, published long fince, in regard to the exig- 
ence of the fnnultaneous affluence and effluence, and 
confequently the double current, of the eleCtric matter, 
in oppofite directions. And herein our author, by a 
feries of experiments, obviates fome doubts, which 
had occurred to Mr. Necker, in relation to the validity 
of this hypothecs. 
The fecond letter is addrefled, as the former was, 
to M. Necker of Geneva. In this letter, the hypo- 
thecs of M. Jallabert of Geneva, a very worthy mem- 
ber of this Society, in relation to the eleCtrical phe- 
nomena, is examined ; and fuch part of it, as does not 
coincide with the ideas of our author, he endeavours 
to confute by an ingenious feries of deductions. 
The third, fourth, and fifth Letters are addrefled 
to M. Du Tour, of Riom in Auvergne, who has 
been a diligent enquirer into the nature and proper- 
ties of electricity. In the firft of thefe, is a careful 
examination of the validity of the doCtrine of plus and 
minus in bodies electrified. So early as in February 
1745, I communicated to the Royal Society an ex- 
periment, and fome deductions therefrom, which laid 
the foundation of this doCtrine. This experiment, 
and the deductions in confequence of it, were after- 
wards printed in the Philolophical TranfaCtions *. 
Thefe I explained more at large, both by experiments 
and obfervations, in another paper, read to the Society 
in February 1745-6 -j-, and were the experiments, 
which fo early caufcd me to conceive, that there was 
* Vide Vol. XLIV. p. 739. 
t Sec Phil. Tran f. Vol. XLV. p. 93 — 101. 
fomething 
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