Page:A complete course in dressmaking (Vol. 12, Men's clothes & index) (IA completecoursein00cono).pdf/94

 and the residue will give an idea of the amount of cotton present.

To Identify Silk when Associated with Cotton or Wool: The boiling-out test as given above for wool and cotton may be aplied to silk and cotton since silk is soluble in lye and cotton is not. One can readily identify silk in a wool mixture by the appearance of the fibers.

To Tell the Difference Between Silk and Artificial Silk: The three following tests may be applied:

(1} Pull out single yarns from the cloth and burn. Silk, an animal fiber will burn slowly and give a disagreeable odor; artificial silk, a vegetable fiber, will flame, burn quickly, and give almost no odor or the odor of burning wood.

(2) Moisten a yarn and try to pull it apart. As we learned previously, artificial silk fibers are very weak when wet and can be easily torn, while the strength of silk is not affected by moisture.

(3) The boiling-out test may also be used to distinguish between silk and artificial silk. Silk, an animal fiber, will readily dissolve in