20 USEFUL FIBER PLANTS OF THE WORLD. 



of mineral constituents than the fibers, and an admixture of the former 

 therefore raises the percentage. 



Hydrolysis. — There are two classes of reagents which intensify that 

 resolving action of water upon organic bodies known as hydrolysis; 

 they are the acids and alkalis. The destructive action of acids has not 

 been included in the scheme of analysis. The action of boiling dilute 

 alkalis, however, effecting a simpler resolution and involving very 

 Important points in the practical applications of the fibers, gives results 

 which form a necessary part of their diagnosis. 



Example of treatment: The fiber is boiled (a) for five minutes in a 

 solution of caustic soda (1 percent Xa 2 0), washed, dried, and weighed — 

 the loss of weight presents the proportion of the fiber which yields to 

 the solvent action of the alkali; (b) in a second portion the boiling is 

 continued for one hour — the loss of weight is an indication of the 

 ''degrading" action of the alkali. In many of the pecto-celluloses the 

 hydrolytic action of the prolonged boiling is such that the noncellulose 

 is almost completely dissolved away. The power of resistance of a 

 fiber to the action of bleaching processes, as well as the resisting of 

 ••wear" of the manufactured fabric in subsequent washings (launder- 

 ing), where strong alkaline soaps or even chemicals are used, is shown. 



Cellulose. — Celluloses, although similar in external characteristics, 

 are of widely different chemical constitution, and vary considerably in 

 their r>ower of resisting the further action of oxidizing and hydrolytic 

 action. A determination of the value and composition of cellulose is 

 made as follows: A fresh specimen having been boiled in the dilute 

 alkali 1 per cent Xa 2 0), is well washed and exposed for one hour, at 

 the ordinary temperature, to an atmosphere of chlorine gas. It is then 

 removed, washed, and treated with a solution of sodium sulphite, 

 which is slowly raised to the boiling point. After two or three min- 

 utes' boiling, it is washed, on a filter when necessary, though in most 

 cases it may be so placed in a funnel as to act as its own filter. Lastly, 

 it is treated with dilute acetic acid, washed, dried, and weighed. The 

 percentage yield on the raw fiber is the most important criterion of 

 its composition and value. 



Mercerizing. — This refers to the action of concentrated solutions of 

 the alkalis upon vegetable fibers, particularly the compound libers or 

 those which are made up of a number of fibrils aggregated into a bun- 

 dle, the larger portion of fiber consisting of such bundles. The action 

 of the alkali often causes a very profound change in structure, not 

 only dissecting the bundles, but altering the contour of the fibrils. 

 The treatment takes its name from Mercer, whose original studies were 

 for the determination of the structural modification which cotton under- 

 goes when treated with strong alkalis. 



Nitration. — When a fiber is exposed for one hour to a nitrating acid, 

 such as a mixture of equal volumes of concentrated nitric and sul- 

 phuric acids, one of the most important results which follow is an 



