350 LEWIS V. HEILBRUNN. 



lipoid solvents. The surface tens'on of some of these substances 

 is listed in Landolt and Bornstein, " Physicalische Chemische 

 Tabellen." 



Substance. Temperature, Surface Tension (Dynes 



per Cm.) 



Chloroform 20 26.72 



Toluol 17-5 28.52 



Benzol 20 30.2 



Xylol 15.7 28.97 



Ether 20 16.49 



Alcohol 20 22.03 



Amylene 1 16.5 17.21 



Phenol 36.5 4i-3 



It will be noticed that the first four of these substances are 

 practically insoluble in sea-water. Herbst found that chloro- 

 form and toluol must be shaken with sea-water to produce the 

 necessary effect. 



Distilled Water and Dilution of Sea-water. The surface ten- 

 sion of distilled water is 75 dynes per centimeter. The addition 

 of inorganic salts always increases the surface tension gradually 

 in proportion to the concentration of each salt present, and, by 

 the work of Valson, Rontgen and Schneider, Whatmough, 2 etc., 

 we should estimate the surface tension of sea-water at approxi- 

 mately 77 dynes per centimeter. Hence diluted sea-water and 

 distilled water have a somewhat lower surface tension than sea- 

 water, and it is to this fact that I attribute their action in 

 causing membrane elevation. 



Isotonic Salt Solutions. Lillie 3 first showed that pure isotonic 

 (i. e., 55M) solutions of sodium salts caused membrane elevation, 

 the order of effectiveness of anions being that of the lyotropic 

 series, Cl > Br > C1O 3 > NO 3 > CNS > I. The effect of these 

 salts was inhibited by CaCl 2 and MgCl 2 . It was shown by 

 Whatmough 4 and others that equivalent normal solutions of 



1 The surface tension of amylene is not given in Landolt and Bornstein, so I 

 have taken the value given in Castell-Evans 1 Physico-Chemical Tables. Creosote 

 is not included in the list as it is a mixture of various substances; most of these, 

 however, have a lower surface tension than water. 



- Valson, Ann. de chem. et de phys. (4), XX., 361 (1870); Rontgen and Schneider, 

 Wied. Ann., XXIX., 165 (1886); Whatmough, Zeit. f. phys. Chem., XXXIX., 129 

 (1902). 



3 R. S. Lillie, Amer. Journ. Physiol., XXVI., 106 (1910). 



4 Loc. ci',. 



