Colloids and the ultramicroscope : a manual of colloid chemistry and ultramicroscopy / by Richard Zsigmondy ; authorized translationby Jerome Alexander.

  • Zsigmondy, Richard (Richard Adolf), 1865-1929.
Date:
1909
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Licence: In copyright

Credit: Colloids and the ultramicroscope : a manual of colloid chemistry and ultramicroscopy / by Richard Zsigmondy ; authorized translationby Jerome Alexander. Source: Wellcome Collection.

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    üke an electrolyte, nevertheless its aqueous Solutions act as hydrosols. In the second dass, in addition to the Solutions of fuchsin and methyl violet before referred to, bclong the Solutions of neutral red, Capri blue, and picric acid. Michaelis is of the opinion that the granules visible in them are not due to an impurity but to an integral constituent of the solution. He bases this opinion on the fact that particles microscopically visible are too profusely and too regularly distributed in the fluid to be regarded as an impurity.1 1 This view is supported observations made on Solutions of gly- cogen, benzopurpurin, and others. The Solutions of benzopurpurin, for instance, sliow with sunlight sometimes a light-cone resolvable into a large number of bluish-green particles, and at other times a light-cone of the same color, due to amicrons. A freshly prepared solution of this dye-stuff appears turbid because of large particles. In a dilute solution of fuchsin which liad stood long enough I could see but few particles, and therefore considered the particles seen by other investigators to be impurities. Solutions of glycogen at the beginning show in the ultra-apparatus niore ultramicrons than upon standing. (Raelilmann, Gatin-Gruzewska, and Biltz.) J. Lemanis- sier observed the same thing with hsemoglobin solution. (L’etude des corps ultramicroscopiques, Paris, 1905, Jules Rousset). The solution of hannoglobin at first shows a large number of submicrons, but after forty-eight hours hardly a particle is left. According to Lemanissier this change is not due to a Chemical alteration of the luemoglobin. These observations indicate that with many substances the course of solution is a double one, crystalloidal solution occurring simul- taneously with a colloidal solution, which for its part may consist either of submicrons or amicrons. From this it is quite evident that determinations of molecular weights with aqueous Solutions of fuchsin, methyl violet, etc., made by Ivrafft (Ber. d. D. ehern. Ges., 1889, Vol. XXXII, p. 1612), would lead to a higher molecular weight than determinations with Solutions of the same substances in alcohol. With these substances the disappearance of ultramicrons may perhaps be due to a gradual transition from colloidal into crystalloidal solution. With other substance there seems to be a Splitting up of submicrons into amicrons, according to the idea of Donnan (Chap. XXI). As may be seen, there are still numerous unsettled questions regarding the