212 PHILOSOPHICAL TRANSACTIONS. [aNNO 1787. 



with a few green leaves in the sun, had acquired a greenish cast, and which I 

 found was disposed to yield dephlogisticated air in great abundance, I filled a 

 globe, containg46 cubic inches, with this water, and putting to it two healthy 

 peach leaves, exposed .the globe in the sun on September 7, from 1 1 o'clock in 

 the morning till 2 o'clock in the afteraoon (3 hours), when -^V of a cubic inch of 

 air was produced, which, proved with nitrous air, gave la -f 3?z = 1.^2, 

 or 248 degrees. A like globe, with fresh spring water and two peach leaves, 

 exposed at the same time, furnished only -^ of a cubic inch of air, which, on 

 account of the smallness of its quantity, I did not submit to the test of 

 nitrous air. 



Exper. 3 1 . Sept. 8, very fins clear weather, but rather cold for the season. 

 Three equal globes, a, b, and c, containing each 45 cubic inches, were filled as 

 follows, and exposed in the sun from Q o'clock in the morning till half an hour 

 past 4 in the afternoon, when they were found to have produced air as under- 

 mentioned. 



The globe a, filled with water, which, by being previously exposed in the 

 sun for several days, with potatoes cut in thin slices, had turned green, furnished 

 jSg- of a cubic inch of air of 299 degrees, or la + 3^ = 1-01. n. b. This 

 water, before it was put into the globe, was strained through two thicknesses of 

 very fine Irish linen. The globe b, filled with the same green potatoe water, 

 strained as before, to which were added 4 middling-sized peach leaves, furnished 

 2i cubic inches of air of 320 degrees, or la -{- 4n= 1.80. The globe c, filled 

 with fresh spring water, with 4 peach leaves, furnished -jVo o^ a cubic inch of 

 air of 151 degrees, or which, proved with nitrous air^ gave la -|- 2?z = I.49. 



To ascertain the quantities and qualities of the airs remaining in the different 

 waters used in this experiment, putting the globes separately over a chafing-dish 

 of live coals, and making the water boil, taking care to hold the globe in such 

 an inclined position as that the air separated from the water might be collected in 

 the upper part of the globe, the airs produced were as follow. 



Quantity. Quality. 



By the green water in the globe a -^ of a cubic inch 280 degrees. 



By the green water in the globe b -^^ 241 



By the spring water in the globe c -^ 68 



The waters in these experiments were made to boil but for a moment ; other- 

 wise, it is probable, more air might have been separated from them. Finding 

 that fresh leaves, exposed to the action of the sun's rays, in water which had 

 already turned green, caused pure air to be separated from the water in so great 

 abundance, I repeated the experiment, only, instead of leaves, I now made use of 

 a small quantity of conferva rivularis ; when I had nearly the same result as with 

 the leaves. To ascertain the relative quantities and, qualities of the airs yielded 



