The Effect of the Chemical Nature of a Decolorizer on Its Functioning. II. the Apparent Isoelectric Point

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Abstract
The isoelectric point of a bacterial system is the hydrogen-ion concentration at which there is equal retention of anion and cation. Defining this point as that at which there is equal retention of acidic and basic stain when acetone is used as a decolorizer, it is shown that acidic decolorizers shift the experimentally determined point to a higher pH-value while basic decolorizers shift it to a lower value. Thus basic decolorizers show abnormally high decolorizing power toward smears stained with acid dyes, and acid decolorizers show the same abnormal behavior toward smears stained with basic dye. By basic decolorizer is meant, not one of high pH-value, but one which will form a salt with acids, as for example pyridin or anilin. This indicates an ionic chemical equilibrium as a factor in the mechanism of staining.