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evidence of this alleged fact, as an observation of the 
volume of gas, to which the former chemists entire- 
ly trusted, but which Mr Dalton seems to have 
wholly neglected. A still greater objection to Mr 
Dalton's experiment arises from the pulverized 
state in which the charcoal was employed, by which 
its porosity, the very circumstance essential to the 
success of the experiment, was destroyed ; a circum- 
stance, however, which he has entirely overlooked. 
Neither will his method of accounting for the gases 
afforded by charcoal, suffice for the present occasion ; 
since water and charcoal could only furnish gases 
composed of oxygen, hydrogen, and carbon, but 
could never explain the production of muriatic and 
many other gases, which his predecessors obtained. 
Lastly, in asserting that, in these experiments, gases 
cannot be expelled at a low temperature, because in 
the experiments of Allen and Pepys they were af- 
forded only at a red heat, Mr Dalton, as we sup- 
pose, has confounded together things which, in 
themselves, are perfectly distinct ; for we know no 
instance in which those chemists have attempted to, 
expel from charcoal the various gases wiih which 
it had been artificially impregnated ; and yielding, 
therefore, entire credit to their results obtained from 
charcoal under ordinary circumstances, no infe- 
rence can thence be drawn against the results of 
other experiments, in which the circumstances are 
totally dissimilar. For these reasons, we do not con- 
sider the experiment of Mr Dalton as, in the small- 
est degree, invalidating those before related ; and if 
it be considered to prove any thing, it can only prove 
