This article is a timely contribution to a subject which has assumed great importance in recent years. The first chapter gives an historical review of the development of silk weighting together with a bibliography of the patent literature on this subject. The second chapter describes in detail the present-day procedure for the tin weighting of silk both in the skein and the piece. Particular attention is given to the development of new apparatus for weighting silk piece goods. The third chapter deals with chemical analysis and control as applied to the weighting baths and also with the analysis of weighted silks. The fourth chapter compares the relative durability of weighted and unweighted silk and discusses the methods which have been proposed to increase the durability of weighted silk.