Dixon — The Cohesion Theory of the Ascent of Sap. 



57 



perforations, a thermometer and a capillary glass tube were intro- 

 duced, care at the same time being taken that no free air should 

 be enclosed in the bottle, and that the capillary should be full of 

 water. The outer end of the capillary was then arranged so as to 

 dip below the surface of mercury. The mean volume of the 

 capillary, determined by weighing a mercurial index, was per 

 10 cm. = "19 c.c. 



On the next day, November 13th, the position of the mercury 

 index was observed and marked zero. 



This table shows a continuous absorption of water during 

 fourteen days. The irregularities in the rise of the index are to 

 be credited to the fluctuations of temperature, and also partly to 

 the sticking of the mercury in the capillary. 



As might be expected from the manner of treatment, the 

 amount of absorption, as indicated by the movement of the index 

 will show considerable variations in different experiments. Bat 

 all my experiments have shown a comparatively large amount of 

 water absorbed. In the experiment just quoted, the smallest rise 

 of the index for the weight of plaster was observed. In the 

 following a good deal larger absorption is recorded. 



