on the Production of Dephlogifticated /Hr*. j j 5 
the lad fortnight the quantity of air in the jar did not appear to 
be fenf bly increafed. 
The fpring water, during the frft five or fix days, furnifhed 
very little air ; and it was not till the fourteenth day that it 
began to yield it in any confderable quantities. From this 
time it went on to furnifh it, though but very (lowly, till 
about the twenty-fecond day, when it ceafed, appearing to be 
quite exhauded. 
Upon the twenty-eighth day I removed the airs from the jars, 
when I found their quantities and qualities to be as follows : 
Quantity. Quality; 
Air furnifhed by the fpring water 14 cubic inches \a-\- 2 n~ 1,62, or 138 
by the pond water 31! — ia-{- 3** — 1,48, or 252 
Neither the colour of the fpring water, nor that of the 
pond water, appeared to be fenfibly changed ; but both the one 
and the other of thefe waters had depof ted a confderable quan- 
tity of earth, which was found adhering to the furfacesof the 
glafs bafons in which the jars were inverted. 
As thefe bafons were rather deep, and as they were very 
thick in glafs, and confequently not very tranfparent, their 
bottoms, where the fediment of the water was colledted, were, 
in a great meafure, obfcured or deprived of the diredt rays of 
the fun. Sufpedling that this circumftance might have had 
fome effedt, fo as to have hindered the water from furnifhing fo 
much air as otherwife it might have yielded, to fatisfy myfeif 
refpedting this matter 1 repeated the experiment, difpofing 
the apparatus in fuch a manner, that the fediment of the water, 
which attached itfelf to the bottom of the veffel in which the 
jar was inverted, had the advantage of being perfe&ly illu- 
minated. 
Q 2 Expe- 
