218 Experiments on the Production of Air 



Experiment No. 24. 



A globe about 4^ inches in diameter (contents, 46 

 cubic inches) being filled with fresh spring-water, and 30 

 grains of raw silk, which had been used in many preced- 

 ing experiments, and being exposed to the action of the 

 sun's rays two days, in all about 8 hours of sunshine, 

 the weather being cloudy great part of the time, iifo" 

 cubic inch of air was produced, which, proved with ni- 

 trous air, gave I a -}- 3 n = 1.96, or 204. 



Experiment No. 25. 



At the same time an equal globe, containing fresh 

 spring-water, and about 15 grains of poplar cotton 

 (which had likewise been used in former experiments), 

 produced i-jVo cu ^ic inch of air, which, proved with ni- 

 trous air, gave i a -j- 3 n = 1.40, or 260. 



The water in both these experiments had acquired a 

 faint greenish cast ; but the colour of that with the cot- 

 ton was rather the deepest. 



Upon examining this water under a microscope, I found 

 it contained a great number of animalcules exceedingly 

 small, and of nearly a round figure. That with the silk 

 contained them likewise, and of the same kind, but not 

 in so great abundance. I never failed to find them in 

 every case in which the water used in an experiment had 

 acquired a greenish hue ; and from their presence alone, 

 I think it more than probable that the colour of the 

 water, in the first instance, arose in all cases. I have 

 spent a great deal of time in observing them, and 

 have made many experiments upon their production ; 

 but as I have not yet been able to satisfy my own mind, 

 with respect to the part they act in the operation of puri- 

 fying the air in water, or generating pure air from it, I 



