Einige Beobachtungen über die Waschwirkung der Seifen

Spring, W. Zeitschrift fuer Chemie und Industrie der Kolloide (1909), 4, 161-8; SciFinder (Chemical Abstracts Service: Columbus, OH); https://scifinder.cas.org (accessed July 8, 2010).

Objections to Chevreuil's, Hillger's, Falk's, and Knapp's theories for the cleansing action of soap are presented. Experiments on the action of soap sols. on carefully purified lampblack bring out the following facts: Lampblack (charged +) hastens the formation of an acid salt (charged -) then forms an adsorption compound with it. A suspension of lampblack in soap sol. will run through filter paper while lampblack can be filtered from water sol. because of an adsorption compound between it and the filter paper. A 1% soap sol. gives an optimum suspension of lampblack, while a 2% is about equivalent to water. Small amounts of alkali increase the suspending power of a sol. greatly. 0.2-0.16% sols. of soap in MeOH, and 0.05% sol. in EtOH show the same optimum suspension for lampblack. The residue of soap obtained by evaporating a given vol. of sol. is the same, whether C has settled through it or not, but the ash in that residue is greater when C has been present, i. e., the basic part is higher in ash than the acid part. From MeOH the ash is less and the C has combined with the basic soap. From EtOH there is practically no difference. The C settled from soap sol. is a thick sirup, and cannot be purified, but forms a colloidal sol. in H2O. C in H2O is uncharged, but in alkaline sol. is + charged. From a 2% soap sol. a white ppt. of C + acid soap collects about the anode, and is lower in ash than soap obtained from the sol. by evaporation.

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