5^^ Sir H. Davy's Experiments on the 
before and after the experiment was brought to the same 
temperature as the water over which the oxy gene gas had 
remained. And as during the short time required for the 
combustion there was no sensible change either in the ther- 
mometer or barometer, no corrections for pressure or tem- 
perature were rendered necessary ; the change of volume in 
the gas after the combustion, was estimated by means of a fine 
tube connected with a stop-cock, adapted by a proper screw 
to the stop-cock of the globe, and the absorption was judged 
of by the quantity of mercury that entered the tube, which 
afforded a measure so exact that no alteration, however minute, 
could be overlooked. As the elastic force of the vapour of 
water is the same at the same temperature, it was evident, 
that if any w^ater formed in these experiments, it would be de- 
posited as dew or mist in the globe ; and lam convinced by 
V 
direct trials, that a quantity of moisture not capable of being 
weighed by a balance sensible to the ^ grain, is ren- 
dered evident by deposition on a polished glass surface.* 
The diamonds w^ere always heated to redness before they 
were introduced into the capsule. 
During the combustion of the diamond, the glass globe was 
kept cool by the application of water to that part of it imme- 
diately above the capsule, and where the heat was greatest. 
In the first experiment, three diamonds, weighing together 
1.63 grain, were entirely consumed, in a quantity of oxy gene 
• A piece of paper weighing a grain was Introduced into a tube of about the capa- 
city of four cubical inches, the exterior of which was gently heated by a candle ; im- 
mediately a slight dew was perceptible in the interior of the upper part of the tube; 
the paper taken out and weighed immediately in the balance above referred to, had 
not suifered any appreciable diminution. 
