38 Mr. William Henry’s Experiments on the 
recollected, however, that no method hitherto discovered de- 
taches from water all its air; and the unknown quantity 
remaining in it, after these modes of separation have been em- 
ployed, is to be added to that with which a given volume of 
water can be artificially impregnated. Dr. Pearson, in his 
enquiries into the nature of the gas obtained by passing electric 
discharges through water, was at great pains to purify the 
subject of his experiments from air, by boiling and a powerful 
air pump ; but he always found, that after the full effect of both 
these methods, electricity liberated a further, and not an incon- 
siderable, portion of air.* 
Common spring water may, I think, be fairly taken as a 
specimen of water fully charged with atmospherical air ; and, 
with the view of determining the quantity and kind of gases 
extricated from it, I made the following experiment. A glass 
globe, of the capacity of 117-5- cubical inches, was filled with 
water fresh from the well. To its mouth was adapted a curved 
and stoppered tube, which held \ of an inch ; and this was also 
filled with water. The globe was then placed in a vessel of brine, 
which was kept boiling between six and seven hours ; and the 
gases were received over mercury. Their quantity and quality 
were as follows. 
Consisted of 
Proportion of 
Cub. inches. 
■ -v - 
J 
Oxygen gas in the 
No. 
Carbonic acid. 
Air. 
residuary air. 
1 
I.25 
0.50 
0> 75 
0.20 
2 
i.s 5 
O.85 
0.40 
O.lb 
3 
I.63 
1.23 
0.40 
0.16 
4 
O.5O 
O.49 
0.01 
lost by acci- 
— 
— 
dent. 
4.63 
3-°7 
1.56 
Air remaining in ' 
to *7 se 
the bent tube _ 
\ u '75 
5.38, total gas from 117I- inches of water. 
* Phil. Trans, for 1797. 
