Abstract
Bancroft 1 recently reported some conclusions drawn from unpublished data of a Mr. Cartledge who dried gelatin gels of different concentrations down to a 96 per cent. gelatin content and then allowed these dried sheets to again imbibe water. It was found that “each swelled rapidly to the original concentration and then took up water slowly.”
We have conducted experiments similar to those of Cartledge and have secured comparable results. Thus a 10 per cent. gelatin gel dried down to less than 3 per cent. moisture content had imbibed at the end of 72 hours 6.45 grams of water per gram dry gelatin as contrasted with 4.30 grams water for a 40 per cent. gel similarly treated. Comparable differences were observed when the dried sheets were ground and uniform sized particles sieved out and tested for hydration rate and maximum hydration capacity.
Our experiments indicate that gelatin gels have a structure and that this structure is fixed at the time of gelation and is not appreciably altered by drying the gel at room temperature. A crystal structure in which the gelation temperature is actually the melting point of the crystals would explain the peculiarities observed.
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