76 COMPLETE INSTRUCTION IN 



and phosphate of soda, and a variety of other 

 substances, all more or less injurious to the 

 wear of the fabric, has reached such a height, that 

 it is seriously affecting the trade. This is 

 especially the case as regards black silks, but 

 fabrics of other colors suffer in the same manner. 



It used to be said that a silk dress or a silk 

 handkerchief would last a lifetime, and this is 

 almost true where one can obtain the pure silk. 

 But in much of the fabric sold as silk at the 

 present day there is not more than ten to twelve 

 per cent of real pure silk, all the rest being 

 extraneous matter applied to the fiber in the 

 deceptive process of "weighting." 



Pure silk, when burned, leaves a quantity of 

 ash, which is always considered less than one 

 per cent, but the ash left by some weighted silks 

 has been found to amount to as much as forty- 

 eight per cent of the weight of the fabric. 



The extraneous substances to which we have 

 alluded are caused to adhere to the fiber by 

 passing the skeins of silk through hot baths of 

 tannin, extracts of tin, salts, salts of iron, anti- 

 mony, potash, etc., and it has been found that 

 when a silk heavily charged with such sub- 

 stances is heated, it will not burn with flame, 

 but will only smolder away, leaving a very large 

 amount of ash behind. 



