SALT EFFECTS IN BACTERIAL GROWTH I. PRELIMINARY PAPER

Abstract

The Hofmeister series shows the effects of ions of neutral salts upon the coagulation of colloids and upon the swelling and other physical properties of proteins. Our knowledge of these ion effects in solution has been greatly extended by Freundlich and his students. They noted that the ions could be arranged in a definite order with respect to their effects upon compressi-bility, surface tension, solubility, viscosity, absorption, ratio of reaction, etc. Freundlich seems to favor the hydration theory of salts as an explanation of this neutral salt action, and since the properties affected are so closely related and bound' up with one another, and the ions so consistent in their order of effect, he calls these effects "lyotropic" effects. The lyotropic explanation does not lay claim to being a full explanation of neutral salt action, but it does lay claim to correctness in that it systematically treats complicated phenomena. In most cases the influence of the anion far outweighs that of the cation and the order of anion effects usually reads as follows, F> S04> P04> Cl> NO3> I> CNS; while the order of arrangement for the cation is usually Ca> Sr> Mg> Cs> K> Na> Li. The same sequence is obtained in the widely differing changes mentioned above and does not seem to follow any recognizable order with respect to valency, atomic weight, etc. Certain reagents may promote or hinder the salt effects as compared with those in pure solution. In some cases the Published with the permission of the Secretary of Agriculture.