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(fuch is the condition of humanity!) error too fre- 
quently intrudes herfelf, and fpoils the work. 
My very refpeCtable antagonift, Mr. Eeles, to 
whofe ear, I am convinced, the voice of truth is 
more agreeable than that of applaufe, will forgive 
me the following critique on his performance ; as 
by that means, I am perfuaded, the probability of 
his notions will be intirely deftroyed, and the fore- 
going theory receive additional fupports. 
For this purpofe our firft endeavour will be to 
(hew the uncertainty of fome of the mod: material 
principles, that fupport his arguments * and after- 
wards, the fallacy of the experiments he has given 
us. 
Fir ft then, in page 130. Mr. Eeles has afterted, 
that the greateft poflible rarefaction of water is when 
it boils. I think it might be faid, with equal pro- 
priety, that the greateft rarefaction of folids was 
when they began to melt : and this may indeed be 
verbally true, if we chufe to alter the names of 
bodies, when they undergo any alteration by fire : 
fo folids take the name of fluids, when they are in 
fufion ; and water the name of vapour, when it is 
greatly rarefied in the fteam-engine. Whence we 
find this aflertion feems to be founded on a con- 
fufion in terms, and the faCt far from being exiftent 
in nature. 
In page 133. the fphere of eleCtrical activity is 
laid to be increafed by heat. If by eleCtrical activity 
is here .meant an increafe of its repulfive power (the 
thing, which feems to be wanted in Mr. Eeles’s hy- 
pothefis), I know no experiment to (how it. If it 
be meant, that it is capable of being attracted to a 
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