Section III., 1885. 1 21 1 Trans, lluv. Soc. Canada. 



V. — On the Analysis of Silk. — Quantitative Usiimation of Sill- m a Mixed Texture. 



By Dr. H. A. Bayne, Royal Military College, Kingston. 



(Read May 25, 1SS5.) 



Silk is soluble iu concentrated acids, both inorganic and organic, in alkaline solutions, 

 and in certain other reagents, as. basic zinc chloride, ammoniacal solution of oxide of cop- 

 per or oxide of nickel, etc. It was my endeavour to ascertain to what extent these 

 reagents also affect other fibre which may be woA'^en in with silk, fraudulently or other- 

 wise, and in this way to determine how the silk in a mixed texture may, with reliability, 

 be ascertained quantitatively. 



Method of Proceditre. — Samples of pure silk, wool, cotton, and linen, were selected. 

 Their purity was determined by the examination, under the microscope, of fibres taken 

 from both warp and woof. The silk used in the greater portion of the analyses was the 

 silk employed in the manufacture of cartridge bags for the British serA'ice, and warranted 

 absolutely free from foreign fibre. This purity is recjuisite in this manufacture in order 

 to prevent " smouldering" or " holding fire," — a property belonging to other fibres, (par- 

 ticularly to cotten and linen), but from which silk is free. 



"Weighed samples of each variety of cloth were carefully dried at 100' C, and then 

 treated with alcohol or ether and afterwards with dilute (1%) hydrochloric acid to remove 

 any traces of greasy matter, weavers' dressing, or colouring matter in the fibre ; then again 

 dried at 100' C. and weighed, and subsequently all four samples submitted together to the 

 action of the same reagent. After a second treatment with acidulated water or dihite 

 alkaline solution and frecjueut washing, the samples were redried at 100' C. and the per- 

 centage of loss estimated. 



Solvent Action of Acids. — Concentrated nitric acid (cold) dissolves silk, but acts 

 too energetically on other fibre also to aflord a means of separation. The same may be said 

 of concentrated chromic acid. Concentrated sulphuric acid seemed not so readily to 

 dissolve silk and wool, while cotton and linen are converted into gummy substances 

 soluble iu water. Concentrated phosphoric acid (hot) dissolves silk, but also attacks wool 

 and carbonizes cotton and linen. Very concentrated, boiling oxalic acid and tartaric acid 

 solutions dissolve silk, but also act upon woollen fibre. 



Melted oxalic, tartaric, and citric acids dissolve silk with great ease. The silk con- 

 tracts rapidly to small biilk when put into melted oxalic acid and c|uickly dissolves. 

 Unfortunately for this solvent of silk, wliidi A. Lidow {Journal der ruasischen jihyschem. 

 GeselL, 1884, Vol. I. p. 280,) has proposed as a method of determining the proportion of silk 

 in a mixed texture, the reagent also acts energetically irpon wool ; and cotton and linen, 

 while not affected to the same extent, become disintegrated. Lidow intimates that wool 

 is not attacked, and cellulose only very slightly attacked. This was not found to be sub- 



