552 



Prof. A. J. Brown and Mr. F. P. Worley. [Aug. 9, 



A series of experiments was made in which seeds of Hordeum vulgare 

 were steeped in "weight normal" solutions of ethylic acetate at different 

 temperatures as in the experiments previously described. Curves repre- 

 senting the rate of absorption in these experiments are plotted in the 

 diagram (III) from the values given in the preceding table. 



It will be noticed that the curves resemble very closely in form the water 

 curves (Diagram I), but their general course tends to run at a higher level, 

 indicating an acceleration in the velocity of absorption in the presence of 

 the acetate. 



The values expressing the velocity of entry of water into the seeds were 

 determined, as in the earlier experiments with water alone, from the curves 

 at points representing 7'5, 10, 15, 20, and 25 per cent, of water absorbed. 

 The values so obtained are given in the following table : — 



Table IV. 







Velocity. 









Water already 









Velocity at 21 -1° 



Velocity at 34 -6° 



absorbed. 



At 3 -8°. 



At 21 -1°. 



At 34 -6°. 



Velocity at 3 -8° " 



Velocity at 21 -1° - 



per cent. 













7-5 



0-575 



2-12 



5-25 



3-69 



2-48 



10-0 



0-505 



1 -72 



4-27 



3-41 



2-48 



15-0 



0-406 



1 -23 



3-26 



3-03 



2-71 



20 -0 



0-337 



0-99 



2 -18 



2-94 



2-77 



25-0 



0-274 



0-76 



1 -55 



2-77 



2-04 





2-50 



On plotting the logarithms of these values the results shown in Diagram IV 

 were obtained. 



It will be noticed how closely the lines approximate to straightness, 

 indicating that the velocity of absorption of water from a solution of ethylic 

 acetate is an exponential function of the temperature as in the case of the 

 experiments with water alone. Furthermore, as in the previous case, the 

 slope of the lines is practically the same as that for the logarithms of the 

 vapour pressure of water plotted as a dotted line in the diagram.* 



The only noticeable point in which the results obtained with " weight 



* The form of the curves in Diagrams I and III is very approximately hyperbolic. 

 Making use of this fact, it is possible, by plotting against the time the logarithms of the 

 amount of water finally absorbed minus the amount absorbed at any given time, to arrive 

 at the relative initial rates of absorption. Proceeding in this way, results similar to 

 those described above are obtained. 



