198 Experiments on the Production of Air 



ascertain, this fact, I took a globe A, similar to that made 

 use of in the foregoing experiment, and having filled it 

 with fresh spring-water, I introduced into it 30 grains of 

 raw silk, and placing it with its cylindrical neck inverted 

 in ajar filled with the same water, I covered the whole 

 with a large, inverted earthen vessel, and exposed it, so 

 covered up, for several days, in my window, by the side 

 of another globe B, containing a like quantity of water 

 and silk, which I left naked, and consequently exposed 

 to the direct rays of the sun. 



The result of this experiment was, that the water and 

 silk in the globe exposed to the sun's rays furnished air 

 in great abundance, as in the experiment before men- 

 tioned ; while that in the globe covered up in darkness 

 produced only a few very inconsiderable air-bubbles 

 which remained attached to the silk. 



Experiment No. 3. 



To see if heat would not facilitate the production of 

 air in the globe sheltered from the light, I now removed 

 it from the window, and placed it near a German stove, 

 where I kept it warmed to about 90° of Fahrenheit's 

 thermometer for more than 24 hours ; but this was all 

 to no purpose. The air produced v^'as so exceedingly 

 small in quantity that it could neither be proved nor 

 measured, there being only a few detached air-bubbles 

 which had collected themselves near the top of the globe. 



The mean heat of the water in the globe exposed in 

 the sun's rays, at the time when it furnished air in the 

 greatest abundance, was about 90° Fahrenheit. It was 

 sometimes as high as 96^ ; but air was frequently pro- 

 duced in considerable quantities when the heat did not 

 exceed 65° and 70°. 



