VOL. LXXVII.] PHILOSOPHICAL TRANSACTIONS. 203 



pea plant with 3 leaves on it ; both which vegetables furnished air in the same 

 manner as they are known to furnish it when exposed, under similar circum- 

 stances, to the action of the sun's direct rays, but in less quantities, which I 

 attribute to the greater intensity of the sun's light above that of my lamps. 



After describing some additional contrivances, to render the globes, &c. more 

 convenient. Sir B. says, finding that raw silk, exposed in water to the action of 

 light, causes the water to yield pure air in so great abundance, I was desirous of 

 finding out whether this arose from any peculiar quality possessed by the silk ; or 

 whether other bodies might not be made to produce the same effect : to this 

 end, having provided 6 globes, each about 44- inches in diameter, and having 

 filled them with fresh spring water, I introduced into them the following sub- 

 stances, and exposed them all, at the same time, to the action of the sun's rays. 



In the globe N° i I put 15 grains of sheep's wool, 



N° 2 15 grains of Eider down, 



N° 3 15 grains of the fine fur of a Russian hare, 



N° 4 •. . . . 15 grains of cotton wool, 



N° 5 15 grains of lint, or the ravellings of fine linen, 



N° 6 15 grains of human hair; these substances being 



all well washed, and being thoroughly freed of air, by being wet before they 

 were put into the globes. 



The results of these experiments were as follows : 



Exper. Q. The globe N° 1 , which contained the sheep's wool, did not begin 

 to furnish air in any considerable quantity till the 3d day of its being exposed 

 to the action of the sun's rays ; and several days of cloudy weather intervening, 

 I did not remove the air till the 8th day, when I collected 1|- cubic inch, which 

 proved with nitrous air, gave 1« -f- 3w = 1.28, or 272 degrees. The wool at 

 no time furnished more than 4. part of the air, which an equal quantity of silk 

 would have furnished under the same circumstances. 



Exper. 7. The water in the globe N° 2, with the Eider down, began almost 

 immediately to furnish air, and continued to yield it during the whole time of 

 the experiment, nearly in as large quantities as the water with silk had done in 

 the former experiments, and nearly of the same quality. 1|- cubic inches of 

 this air, furnished the 8th day from the beginning of the experiment, or the 3d 

 of sunshine, proved with nitrous air, gave la + 3w = 1.34, or 266 degrees of 

 purity. 



Exper. 8. The globe N° 3, with the hair's fur, which was white, furnished 

 more air than the sheep's wool, but not so much as the Eider down. After 4 

 days of sunshine, I collected 2 cubic inches of this air, which, proved with 

 nitrous air, gave 1 o -j- 3?? = 1 .44, or 256. 



Exper. 9. The globe N° 4, with cotton wool, furnished a considerable quan- 



D d2 



