Abstract
GELATINE-WATER-ALCOHOL and agar-water are colloidal mixtures which form a gel on cooling and a sol on warming. In both cases the formation of the gel is due to the separation of the fluid mixture into two partially miscible fluids or phases. When a certain critical temperature is reached, one of the phases separates out as a cloud of droplets. With a further fall of temperature either this internal phase or the external phase becomes a solid solution, and forms a framework in the spaces of which the still fluid solution is lodged. Thus two distinct types of gel occur. In the one the structure is a solid mass, in which are embedded spherical spaces filled with fluid. In the other it is an open sponge-work of adherent solid spheres with fluid filling the meshes. The former is firm and elastic, the latter is brittle and undergoes spontaneous shrinkage. In the ternary mixture the gel has the former structure when the gelatine content of the mixture is high; the latter when it is low.
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On the Mechanism of Gelation, and on the Stability of Hydrosols 1 . Nature 61, 599 (1900). https://doi.org/10.1038/061599a0
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DOI: https://doi.org/10.1038/061599a0