22 2 Experiments on the ProdAtction of Air 



and placed in the middle of the garden of the Elector's 

 palace at Munich, where it was left' exposed to the 

 weather 28 days. 



At the same time another like jar was filled with 

 water taken from a pond in the garden, in which many 

 aquatic plants were growing, and was exposed in the 

 same place, and during the same period. This water 

 had a very faint greenish cast. The pond from which it 

 was taken is fed by a large river (the Isar) which runs 

 by the town. 



The second day after these waters had been exposed in 

 the sun, I observed that a small quantity of air had col- 

 lected itself at the upper part of each of the jars. 



The third, fourth, and fifth days, the pond-water fur- 

 nished air in pretty large quantities ; and it went on to 

 yield it without intermission, when the sun shone upon 

 it, till the fourteenth day, when it seemed to be nearly 

 exhausted. I continued the experiment, however, till 

 the twenty-eighth day, though, during the last fortnight, 

 the quantity of air in the jar did not appear to be sensi- 

 bly increased. 



The spring-water, during the first five or six days, 

 furnished very little air ; and it was not till the four- 

 teenth day that it began to yield it in any considerable 

 quantities. From this time it went on to furnish it, 

 though but very slowly, till about the twenty-second 

 day, when it ceased, appearing to be quite exhausted. 



Upon the twenty-eighth day I removed the airs from 

 the jars, when I found their quantities and qualities to 

 be as follows : — 



Quantity. Qualitj'. 



Air furnished by the spring-water 14 cubic in. i ^ -j- 2 ;? = 1.62, or 13S 

 " " " " pond " 31! " itf -1-3;? = 1.4S, or2S2 



