II. THE BEAHING OF OSMOTIC PRESSURE ON THE 

 DEVELOPMENT OF PHYSICAL OR GENERAL 

 CHEMISTRY! 



HARRY C. JONES 

 The Johns Hopkins University, Baltimore, Md. 



The task that has been set me is an easy one. There is no 

 other property of solutions which has played so prominent a 

 role as osmotic pressure in the development of modern physical 

 or general chemistry. 



The young Dutch chemist, Van't Hoff, was called at the age 

 of twenty-four from Utrecht to .\msterdam to the chair of chem- 

 istry in the latter institution. Van't Hoff, even when a pupil 

 with Kekule in Bonn, was not content with the chemistry of his 

 time. It did not appear to him to lead anywhere. To bring 

 certain things together, to allow them to react chemically and 

 then simply to determine the nature and properties of the prod- 

 ucts formed, did not appeal to him as sufficient, even if these 

 steps were necessary to develop a branch of natural science. 

 He wanted to know something about the nature of the reactions 

 which gave rise to these products. He wanted to know at least 

 the velocities with which these reactions take place, and the con- 

 ditions which existed when equilibrium was reached. In a word, 



1 At the Cleveland meeting of the Botanical Society of America a symposium on 

 Permeability and Osmotic Pressure was held, in which the following subjects were 

 discussed: 



I. Osmotic pressure and semi-permeability in animal cells. Jacques Loeb. 



II. The bearing of osmotic pressure on the development of physical or general 

 chemistry. Harry C. Jones. 



III. Quantitative researches on the permeability of plant cells. W. J. V. Oster- 

 hout. 



rV. Osmotic pressure and related forces as environmental factors. Burton E. 

 Livingston. 



The paper of Professor Loeb will be published later. 



73 



THE PLANT WORLD, VOL. 16, NO. 2, MARCH. 1913 



