ON THE LUSTRE OF ARTIFICIAL SILK.

Abstract

Dr. A. Herzog has already described that the lustre of artificial silk is chiefly decided by the optical structure of surface, the construction and transparency of a thread and the titre of a single filament. The reflection by cellophane occures most remarkably for the normal direction, and it is therefore assertained that the surface of cellophane or artificial silk must be nearly optically uniform. The lustre of artificial silk is, of cause, considerably due to the shape of its surface. However, the author now assumed that a single filament of artificial silk is formed of circular cylinder and arranged parallel to each other, and showed on the basis of geometrical optics that the most part of incident light should be regularly reflected and in consquence the thread should have a glaring metallic lustre with the light of parallel direction to yarn, and that the most part of incident light should be irregularly reflected to every direction and in consquence the thread should have a glassy and aventurine lustre with the light of perpendicular direction to yarn. The experimental results are coincident with this theory.The twist of yarn affects also remarkably the lustre, and with an increase in the twisting dagree the metallic lustre is modified to the aventurine lustre and maximum gloss is shifted to the direction of surface twist.The multiplication of filament, the irregularity of surface, the residual sulphur of viscose silk, etc. also modify the metallic lustre of artificial silk.