. ^ 



216 Experiments on the Production of Air 



46 cubic inches, being filled in the evening with fresh 

 spring-water, and 30 grains of raw silk, which had been 

 previously washed thoroughly to free it of air and the 

 remains of former experiments, and being exposed the 

 next day in my window, the weather being cold and 

 cloudy, with not more than one hour of sunshine, \ of 

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

 trous air, gave i a-\- 2 n 1.86, or 114. 



The two following days, the weather being clear and 

 moderately warm, 3-*- cubic inches of air were produced, 

 which, proved with nitrous air, gave i a -j- 3 = i-i4> 

 or 296. 



Experiment No. 18. 



The globe having been again filled with fresh spring- 

 water, and the same silk which had served in the last 

 experiment, after 2 nights and i day of about 4 hours 

 sun, it had furnished \\ cubic inch of air, whose quality 

 was i a -J- 2 n = 1.13, or 197. 



The two following days, the weather being very fine, 

 it furnished 3^-$ cubic inches of air, which, proved with 

 nitrous air, gave i a -j- 4 n 1.58, or 342. 



Experiment No. 19. 



The globe being again filled with fresh water, and the 

 same silk well washed, and being exposed two days in 

 the sun, it gave 2 T 2 y- cubic inches of air, which, proved 

 with nitrous air, gave i a -{- 3 n = 1.67, or 233. 



Experiment No. 20. 



A like globe with fresh water, and an equal quantity 

 of poplar cotton which had been used in former experi- 

 ments, being exposed at the same time (viz. when the 



