240 grams of sericin prepared from cocoon fibre of silk worms were hydrolyzed; and the aminodicarboxylic acids and diamino-acids in the hydrolyzate were determined. Thus it was found that, the total molal quantity of the aminodicarboxylic acids was twice as much as that of the diamino-acids, a result which may be worthy of attention in view of the fact that sericin is a protein of comparatively stronger acid nature with its isoelectric point of pH=4.
