Abstract
The study of one of us 1 on the adsorption of bacterial polysaccharides on colloids as antigens suggested further study of the adsorption isotherms of some of these substances, to see if they follow the type of curve usually obtained in adsorption experiments. In the previous work 1 collodion particles, aluminium hydroxide, casein and bacterial cells were used as adsorbents, but in all of these substances with the exception of aluminium hydroxide the adsorption is so slight as to be hardly detectable.
The adsorptive power of charcoal exceeds that of other adsorbents and with this fact in mind as well as the successful immunizing effect which Landsteiner and Jacobs 2 found using this substance as adsorbent with the polysaccharide from V. cholera, we used charcoal (“Norit” obtained from A. H. Thomas and Co.) as our adsorbent and as polysaccharides we used that of anthrax, pneumococcus types I and III.
The amounts adsorbed were determined by the precipitin-test with a specific immune serum, titrating the mixed washings from the adsorbent, using as control the same polysaccharide in known concentrations. By comparing the highest dilution of the unknown which gave a definite precipitate with the highest dilution of the control polysaccharide giving the same amount of precipitate, the amount of polysaccharide in the unknown was determined. This method permits a much more accurate determination of the amount of polysaccharide adsorbed than the present chemical method at our disposal (determination of reducing sugars after hydrolysis).
The formula used for the making of the curves is the one given by Freundlich 3 : a = αc 1/n, where a is the amount adsorbed by 1 gm. of adsorbent, c is the residue in solution of adsorbed substance and α and I/n are constants.
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