EXAMINATION OF TEXTILE FIBRES. 81 
above. The leathery covering of the cocoanut supplies 
a fibre used for matting, etc. Asbestos illustrates the 
possibility of using a mineral substance for textile pur- 
poses. Finally, various artificial fibres are made from 
metals and from cellulose derivatives. 
In the identification of textile fibres the microscope is 
of prime importance. Animal fibres in general may be 
distinguished from those of vegetable origin by the 
fact that both wool and silk are soluble in 5% caustic 
soda, while the vegetable fibres, made up of cellulose, 
are not thus affected. Various color reactions are also 
of value. For the determination of individual fibres, 
however, the microscope is most satisfactory, since even 
of the closely related bast-fibres each has its characteris- 
tic appearance. Furthermore, the quality of different 
samples of the same kind of fibre is evidenced by the 
size, twisting, and external structure of the filaments. 
The effect of chemical reagents and the tensile strength 
of individual fibres under various conditions is studied 
with the aid of the microscope in modern textile labora- 
tories. : 
2. The Cotton-fibre.— The cotton-fibre is the vege- 
table hair borne on the seed of plants of the genus Gos- 
sypium, serving like the down of the thistle for the distri- 
bution of the seeds by wind. These plants belong to 
the Mallow family; some are herbaceous and others 
grow to be bushes twenty feet in height. As the seed- 
capsule opens a rich white boll bursts out, made up of 
the cottonseed with the fibres at its free end. 
The cotton-plant grows well between 45° north and 
