New Experiments on Anomalous Osmosis

Abstract

1. It is impossible to reproduce Loeb's observations on anomalous osmosis with membranes prepared from relatively pure brands of collodion, whereas positive effects can be obtained using collodion containing acidic impurities. 2. The inactive (purer) collodion membranes may be activated by oxidation with NaOBr solution. 3. Properly oxidized membranes give much greater anomalous osmotic effects than those described by Loeb.

The Effects Produced by Diffusion in Aqueous Systems Containing Membranes.

“…Fetcher (33) showed that the potentials actually observed by Meyer et al do not agree quantitatively with those that would be predicted from their theoretical equations, and the discrepancies have been further explained by Sollner and Carr (92). Qualitatively, however, ionized porous membranes are of great interest and diffusion through them may produce striking results, as has been shown by Sollner and coworkers (89,90).…”

“…Ingraham and Visscher (55) suggested that the production of ammonia in the gut and its diffusion into the blood stream where its concentration is held a t a very low level by the activity of the kidneys might provide the necessary electrolyte. Although electrokinetic phenomena are in general reduced by high salt concentrations, anomalous osmosis is shown to the greatest degree by solutions of the order of 0.02 N (89) and the effects are still strong a t 0.16 N , a concentration which is in the physiological range. Although Sollner's work shows that anomalous osmosis might provide a mechanism for the active transport of electrolytes under rather special conditions, there is as yet no positive widence that such a mechanism actually operates in vivo.…”

“…These membranes are made by the adsorption of protamine cations on nitrocellulose membranes. The second type is exemplified by oxidized nitrocellulose membranes (38), where oxidation has produced carboxyl groups presumably on the sixth carbon atom of the glucose residues (89). These carboxyl ions will be accompanied by an equivalent number of sodium gegen ions.…”

“…A mechanism capable of moving the solution was not postulated. Sollner and coworkers (40,87,89) have demonstrated and explained one mechanism whereby diffusion across a membrane can produce large movements of the solution, which may be in the direction of natural osmotic flow but more rapid than normal or may be opposed to this flow. This phenomenon is known as anomalous osmosis and is termed negative (anomalous) osmosis if the fluid movement is initially from the more concentrated to the more dilute solution.…”

The Physical Chemistry of Membranes with Particular Reference to the Electrical Behavior of Membranes of Porous Character. I. The Nature of Physicochemical Membranes—Membranes as Physicochemical Machines; Preparation and Properties of Membranes of Highly Pronouned Electrical Properties

“…After a sufficiently long time the electrolyte concentration on both sides of the membranes is the same, and hydrostatic heads which had developed intermediately have disappeared. The technique of Loeb (15) in his well-known experiments on anomalous osmosis, which we have followed with minor modifications, is as follows (25): Collodion bags are cast in 30 x 110 mm. test tubes and allowed to diy several minutes, the suitable drying time varying with different brands of collodion, even if the same solvent is used.…”