Interfacial forces and phenomena in physiology : being the Herter lectures in New York in March, 1922 / by Sir William M. Bayliss; with seven diagrams.

  • Bayliss, William Maddock, Sir, 1860-1924.
Date:
[1923]
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Licence: In copyright

Credit: Interfacial forces and phenomena in physiology : being the Herter lectures in New York in March, 1922 / by Sir William M. Bayliss; with seven diagrams. Source: Wellcome Collection.

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    removal of dye in histological differentiation is a common practice. When an acidic dye has been adsorbed by paper under the influence of salts, it is very difficult to remove it by washing with water. The charge having been neutralized by the adsorption of ions, these ions are held by electrical forces. To enable them to be removed, something must be done to restore the original negative charge of the paper. It is sometimes possible to do this with alkalis, but the difficulty is that there is always the cation of the alkali present to oppose the effect. It is a curious fact that the phenomena described seem to happen only with col- loidal dyes (or large molecules). Staining with picric acid is unaffected by electrolytes. Perhaps a true chemical compound is formed by this somewhat powerful reagent. If the dye is an electrically charged colloid but not a salt, such as Scharlach R.” a so-called “ indifferent ” dye, which does not form salts with either acids or bases accord- ing to Michaelis, it is affected by salts in the