206 PHILOSOPHICAL TRANSACTIONS. [aNNO 1787. 



than thoroughly phlogisticated air. On the 11 th, 12th, and 13th, 1 cubic inch 

 of air only was produced, and this appeared to be as bad as possible ; for, proved 

 with nitrous air, it gave la + 1« = 2, or O. On the 14th a few air-bubbles 

 only were furnished ; but, notwithstanding these unfavourable appearances, I 

 still continued the experiment, and my patience was amply rewarded ; for the 

 next day, the 15 th, the sun being very powerful, and the weather very hot, the 

 water changing suddenly to a greenish colour, began all at once to give good air 

 in great abundance. In the course of the day 10-,^ cubic inches were pro- 

 duced, which, proved with nitrous air, gave la -|- 3w = 1.43, or 257. June 

 1 6th, a very warm clear day, the globe exposed in the sun, from 8 o'clock in 

 the morning till 5 o'clock in the afternoon, furnished 14-tVo cubic inches of air, 

 which, proved with nitrous air, gave la4"3w= 1.34, or 266. Jun« 1 7 th, 

 cloudy, with intervals of sunshine. The globe with about 4 hours sun gave 

 7^3_4_ cubic inches of air, of a very eminent quality, viz. la -\- 4n = 1.40, 

 or 360. 



The water having by degrees lost its transparency, and having acquired a deep 

 green colour, it broke up this day, and deposited a green sediment ; after which 

 it recovered its transparency, and became almost colourless. It continued, not- 

 withstanding, to furnish air in considerable quantities. June 18th, being 

 exposed in the sun's rays from 8 o'clock in the morning till 2 o'clock in the after- 

 noon, when the heavens became overcast, the globe yielded 6-^-^ cubic inches 

 of air, which, proved with nitrous air, gave la -|- 4ra = J. 44, or 356. June 

 the 19th and 20th, the globe furnished no more than 3^^ cubic inches of air, 

 which, proved with nitrous air, gave la 4- 3n = I.06, or 294; after which it 

 ceased totally to furnish air, and the colour of the water changed to a dead yel- 

 lowish cast, and the cotton assumed the same hue. 



The following are the quantities and qualities of the different parcels of air 

 furnished in the course of this experiment. 



Quantity. Quality. 



On the 10th of June l| cubic inches la + In = 1.65, or 35 



1 1th, 12th, and 13th 1 la + In = 2. or 



14th 



15th 10-^ la + 3«= 1.43, or 257 



16th 14^ la + 3« = 1.34, or 266 



17th 7-j^ la + 4n = 1.40, or 360 



18th 6-^ la + 4ra = 1.44, or 356 



19th and 20th 3-1^5 la -f 3n = I.06, or 294 



Total quantity 44^ Mean quality la + 3» = 1.23, or 277 



To ascertain, with greater precision, the qualities of the air furnished at dif- 

 ferent periods of the experiment, or rather the period when the water begins to 

 give good air; and also to determine the relative quantities and qualities of the airs 



