Concerning the existence of fractions of the sericin in raw silk

The question of the possible existence of several fractions of the sericin of raw silk has been investigated.The relative yields of sericins A and B, obtained after treatment of silk in an autoclave , were found to be dependent on the duration of the treatment.Practically all of the sericin removed in the early stages of autoclaving was in the form generally designated as sericin B. On continuing the treatment, this fraction was rapidly converted into the more soluble form, sericin A. Analyses of the fractions obtained after autoclaving the silk for different lengths of time showed that the alleged sericins A and B are not definite chemical entities, but are substances whose chemical compositions vary with the duration of the autoclave treatment.The results of the investigation show that the sericin fraction s are artifacts, which result from the hydrolytic decomposition of the naturally occurring sericin during its removal from the fiber.