The freezing of gelatin gel

Abstract

"Ash-free" gelatin supplied by the Eastman Kodak Company was used throughout. The actual content of ash was found to be 0·05 per cent. of the dry weight. To prepare gels of known strength, the requisite amounts of gelatin and water were left together overnight and then heated at 60° to 80° C. on a water-bath for the least time required to produce a homogeneous solution. When dissolved in distilled water, the hydrogen-ion content of the gel was found to be 10 ^-4·7 gram ions per litre ( i. e. , p _H = 4·7), which is the iso-electric point for gelatin. Save where the contrary is stated, discs of gel as nearly as possible 1·5 cms. in diameter 0·3 cm. in thickness were used.