194 Experiments on the Production of Air 



Having again exposed the globe, with the same water 

 and silk, in my window, where the sun shone the greatest 

 part of the day, at the end of three days I had collected 

 jf cubic inches of air, which, proved with nitrous air, 

 gave I a^-\- 2 n^=. 1.18 ; that is to say, i measure of 

 this air added to 3 measures of nitrous air were reduced 

 to I.I 8 measure. 



A wax taper, which had been just blown out, a small 

 part only of the wick remaining red-hot^ upon being 

 plunged into a phial filled with this air immediately took 

 fire, and burnt with a very bright and enlarged flame. 



The water in the globe appeared to have lost some- 

 thing of its transparency, and had changed its color to a 

 very faint greenish cast, having at the same time acquired 

 the odour or fragrance proper to raw silk. 



This experiment I repeated several times with fresh 

 water (retaining the same silk), and always with nearly 

 the same result ; with this difference, however, that when 

 the san shone very bright, the quantity of air produced 

 was not only greater, but its quality likewise was much 

 superior to that yielded when the sun's rays were more 

 feeble, or when they were frequently intercepted by fly- 

 ing clouds. The air, however, was always not only 

 much better than common air, but better than the air in 

 general produced by the fresh leaves of plants exposed 

 in water to the sun's rays, in the experiments of 

 Dr. Ingen-Housz ; and under the circumstances the 

 most favourable, it was so good that i measure of it re- 

 quired 4 measures of nitrous air to saturate it, and 2>-^S 

 measures of the two airs were destroyed ; or, proved 

 with nitrous air, it gave i (3-|-4«= 1.35, which, I be- 

 lieve, is better than any air that has yet been produced 

 in the experiments with vegetables. 



