40 



turbid, and suffered thereby a farther loss of bulk. 

 This experiment was repeated, by confining mustard 

 plants in the same manner in jars of air inverted over 

 mercury. The lime-water was, in like manner, ren- 

 dered turbid, and the mercury for two or three days 

 continued to rise into the jars : after a certain time, 

 however, it became stationary, and then began to 

 fall, and the plants when withdrawn yielded a putrid 

 smell. 



32. As by the preceding experiments it is proved, 

 that the pure part of the air disappears in vegetation, 

 and 'that carbonic acid is produced, it is desirable to 

 know the extent to which rhis destruction of the oxy- 

 gen gas proceeds. Some mustard seeds, therefore, 

 which had grown on moistened flannel to the height 

 of an inch, were conveyed into a jar, and supported 

 about half way up it by a small hoop in the manner 

 already described. The jar held 36.5 cubic inches 

 of air, and was inverted into a saucer, in which was 

 placed a small glass-cup, containing one cubic inch 

 of the water of potassa : mercury was then poured 

 into the saucer, so as to surround the mouth of the 

 jar. Three slips of paper, graduated to inches and 

 tenths, were pasted at equal distances on the outside 

 of the jar, to mark the ascent of the mercury : and 

 the whole was set aside in a room where the baro- 

 meter was at 29.2 inches, and the thermometer at 

 61.5. The inside of the jar was presently bedewed 

 with moisture, and, by the close of the twenty- 

 fourth hour, the mercury had risen in it of an 

 inch, bearing up the alkaline solution with it. By 

 the forty-eighth hour, the mercury stood at one inch, 

 when that in the saucer was brought to a level with 



