(1) Notes on colloidon membranes for ultrfiltration and pressure dialysis / by G.S. Walpole. (2) Detection and concentration of antigens by ultrafiltration, pressure dialysis, etc., with special reference to diphtheria and tetanus toxins / by A.T. Glenny and G.S. Walpole.

  • Walpole, George Stanley.
Date:
[1915?]
Catalogue details

Licence: In copyright

Credit: (1) Notes on colloidon membranes for ultrfiltration and pressure dialysis / by G.S. Walpole. (2) Detection and concentration of antigens by ultrafiltration, pressure dialysis, etc., with special reference to diphtheria and tetanus toxins / by A.T. Glenny and G.S. Walpole. Source: Wellcome Collection.

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    A tendency which sometimes occurs to curl up and leave the glass in dry or warm weather may be prevented by painting the edges of the hardening film with “Collodion Flexible B.P.” Now the degree and temperature of nitration determine the physical properties of nitrated cotton to a most marked extent, so that the properties of the film ultimately obtained depend upon a host of factors, of varying degrees of importance, starting with the manner of nitration of the cotton and ending with the pressure applied to it in use. To characterise membranes therefore so that they may be reproduced and their individual properties discussed, the only possible plan is to take in every case a quantitative account of the result of all variables in procedure which are recognised and utilised as such, and by using stock solutions either identical or as similar as possible, and constant conditions, to reduce the other factors as far as is experi¬ mentally convenient to constancy. The variables I have utilised are two in number and both of them are readily controlled and expressed numerically. The first is the weight of dry nitrocotton per sq. cm. (m) of the finished film. This is determined before¬ hand, for the strength and volume of the solution are known as is also the area of the plate over which it is poured. The second is the “wetness” of the resulting film, a property, intimately connected with its porosity, which depends primarily upon the amount of solvent still remaining in the nitro¬ cotton on the glass plate before it is plunged into water. As a numerical expression of the “wetness” (w) of a filter I have found it convenient to use the ratio of its weight to that of the dry nitrocotton it contains. For example, 157 cc. of a 3-5 times diluted “stock” solution of Schering’s celloidin (13*5 per cent, by weight) were poured on to a circular plate 30-5 cm. diameter. Hence m = 0-0082 g. The weight of a circular filter 23-5 cm. across cut out of this sheet was 17-5 g. The weight of dry nitrocotton it contains is therefore 0*0082 x 77 x 23-52 4 Hence = 3-56 g. 17'5 . Ol w= Q = 4-91. 3-56 Direct determinations, by weighing, on small pieces from the remainder of the film after the circular filter had been cut out gave m = 0-0081 g. w = 5-02.
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