APPENDIX B. 



ON THE IDENTIFICATION OF FIBERS. 



By William H. Seaman, M. D. 



It is frequently desirable to be able to ascertain the nature of fibers 

 composing textile goods, to detect mixtures, or for some other reason. 

 The fibers employed in the commercial industries naturally separate 

 themselves into three great classes, of which two, silk and wool, are 

 derived from the animal kingdom, while the vegetable kingdom fur- 

 nishes an immense variety, as the pages of this work testify. 



The means by which fibers may be identified are also grouped under 

 two heads — chemical and microscopical. For many purposes, the 

 methods are combined together, the chemical reactions being carried 

 out and studied on the stage of the microscope. We will first indicate 

 some of the more obvious reactions by which these classes of fibers may 

 be recognized, and then discuss more particularly the microscopical 

 characters of the vegetable fibers by which they may be distinguished 

 from each other. 



As all animal fibers contain nitrogen, which on burning evolves 

 ammonia, recognizable by its smell, a strong smell from a burning fiber 

 not saturated with any nitrogenous substance clearly reveals its animal 

 origin, because vegetable fibers contain so little nitrogen that its pres- 

 ence is not easily made out and they give no ammoniacal odor oil 

 combustion. The vegetable fibers also do not leave any residue, if well 

 burned, while the animal fibers leave a crispy coal. 



Both silk and wool are soluble in strong hydrochloric acid, the solu- 

 tion being hastened by heat, but in dilute acid silk is soluble and wool 

 is not. Vegetable fibers in the same reagent are disintegrated but not 

 dissolved. Numerous processes have been invented for separating 

 vegetable fibers, burs, etc., from wool, in order to clean the wool from 

 seeds and other foreign vegetable matters that would be injurious to its 

 manufacture, and also to permit the reuse of woolen rags, etc.. which 

 have cotton sewing threads in them or that have been made partially of 

 cotton. These processes depend usually upon the destruction of the 

 vegetable matter by acting on the mass with chlorin, or some compound 

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