56 



Saussure's experiments, may with as much justice be 

 attributed to this abstraction of water, as to that of 

 the carbonic acid. 



44. That this event did not arise from the ab- 

 straction of the carbonic acid, is farther proved by 

 the experiments which follow. Two glass-jars, each 

 containing about 4O cubic inches of atmospheric air, 

 were inverted over water, and into each of them 

 was introduced some mustard plants, growing on 

 flannel, which were supported, as before, by a small 

 hoop fixed half way up the jar. Under the hoop 

 in one jar was placed a small cup, containing about 

 an ounce of water of potassa : the other jar contained 

 the growing plants only. In 24 hours, the water 

 in the jar with the alkaline solution had risen 7-1 Oths 

 of an inch, and in 48 hours H inch ; but in the other 

 jar, in the same time, it had risen only 6-1 Oths of an 

 inch. The plants and alkaline solution were now 

 withdrawn under water from the first jar, and five 

 cubic inches of the residual air being then passed in- 

 to the eudiometer filled with lime-water, produced 

 not the smallest discoloration, nor suffered the least 

 diminution in bulk ; but the same quantity of the 

 air of the other jar, being afterwards treated in like 

 manner, rapidly made the lime-water milky, and 

 suffered a loss of nearly l-5th of its bulk. The 

 air of neither jar, after washing with lime-water, 

 experienced any loss of bulk by agitation with the 

 sulphuretted solution of potassa, and in all respects 

 the plants in both jars presented the same appear- 

 ance, a few only reviving on exposure to fresh air. 

 In both these jars, therefore, carbonic acid was 

 formed by the act of vegetation, but in one case it 



