ARTIFICIAL SILK 37 



yarn is passed through strong solutions of caustic lye. 

 The yarn must be at full tension during the whole opera- 

 tion, even until it is quite dry. Mercer's theory of the 

 action of caustic soda is that received to-day, viz., that 

 the mercerized yarn is a hydrate of cellulose, the first 

 action being the formation of a compound of sodium oxide 

 and cellulose. The subsequent washing replaces the 

 sodium oxide by water, which is held by the cellulose like 

 the metallic oxide. Such a theory as this gives us very 

 little light on the matter, and does not explain the differ- 

 ence between the hydrate formed and the original cotton. 

 It can be dyed any color without materially affecting the 

 brilliancy which has been imparted to it by the mercerizing 

 process. 



COLLODION SILK. Several persons have given their atten- 

 tion to the perfecting of the manufacture of collodion silk, 

 among whom are Count Hilaire de Chardonnet, Dr. Leh- 

 ner, and Nobel of cordite fame. The different systems 

 vary only in detail, so I shall describe the most successful 

 one, known as the Chardonnet silk. I first saw this arti- 

 ficial silk at the Paris Exhibition of 1889, where it obtained 

 a "Grand Prix." Previous exhibits were made of artificial 

 silk in 1878, but no commercial success was attained for 

 many years. 



A public company for the manufacture of artificial silk 

 by the Chardonnet process has been formed in England. 

 The factory, extending over two acres, is at Wolston, on 

 the river Avon, near Coventry, and will be capable when 

 filled with machinery of producing 7,000 pounds of silk 

 per week. 



The first stage of manufacture is the nitration of cotton 

 or wood pulp, producing pyroxyline, discovered by Pelouze 

 in 1838. The greatest care must be employed in conduct- 

 ing this operation, as it is the most important one in the 

 whole process; mistakes sometimes occur even at the long 

 established factory at Besancon in France. The process 

 oi nitration of cellulose is the displacement of a few mole- 



