218 Vindication of Dalton’s Theory of (Marc, 
_ 
The original volume of azotic gas = 79 + 129 . 2%, = 82°39 
Ditto oxygen - - - = 21 4 190, 2h 
104°60 
The actual volume of the mixture absorbed by experiment, 
according to Saussure, was about five per cent.; it appears by 
theory to be 4°6; hence the theoretic result falls short of the 
experimental one by a little. 
These four experiments are all that are given on the absorption 
of mixed gases; the results are all as nearly accordant with theory 
as we have a right to expect, two deviating a little on one hand 
and two on the other. It appears then that instead of “ none of 
these corresponding with the theory,” they all corroborate it in as 
striking a manner as if they had been selected out of a large num- 
ber expressly for the purpose of supporting the theory. 
It may be expected from the above remarks that I consider the 
results of the above four experiments as nearly approximating to the 
truth. Itis not so. The absorption of atmospheric air, as well as 
oxygen and azote, I am convinced, is not much more than half 
what Saussure states; but his errors in azote and oxygen being 
nearly proportional, the comparative quantities in the mixture are 
not much affected. 
In fact Saussure is wrong in all the less absorbable gases; his 
method with them is radically bad, that of taking much air and 
little water, and endeavouring to find the air absorbed by working 
the whole volume of air previous to the absorption and the reduced 
volume. It may be specious enough upon paper, but it is not 
practically the most accurate way to obtain one grain of any article 
by first weighing 1000 grains, and then weighing 999 grains from 
that mass. I apprehend Saussure ascertained. the capacity of the 
flask M when dry within: but when filled with air for the experi- 
ment it was wet within, and consequently did not contain so much 
air by the quantity of water adhering to the glass; this circum- 
stance, trifling as it may seem, is nearly sufficient to account for 
‘the differences betwixt his results and miné. 
In making the above assertion I do not mean to maintain that 
the results which Dr. Henry and I obtained are free from inaccu- 
racies; I believe Saussure in one or ‘more instances has corrected 
us in regard to the absorption by waters; as for other liquids it is 
more particularly a case which concerns Saussure and myself, on 
which I shall remark presently; but I do maintain, that the results 
published by Dr. Henry and me are incomparably nearer the truth 
than Saussure’s, particularly with the less absorbable gases. It 
appears to me a great pity that he should have published his results 
without subjecting them to certain checks which could not fail to 
‘present themselves to his observation. For instance, it would have 
been desirable to find that five per cent. of atmospheric air is. 
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