PROTECTING OUR BODIES WITH CLOTHING 



143 



Linen clothing is most satisfactory for wear in 

 warm weather or in tropical climates. This is due to 

 three factors: (1) linen is the best conductor of heat 

 of all textile fibers, (2) linen absorbs moisture from 

 the body rapidly and also permits moisture to evap- 

 orate rapidly from it, and (3) air is able to pass 

 through linen fibers readily. 



Raw silk is a textile fiber of animal origin ob- 



FIG. 225. SHEARING SHEEP IN AUSTRALIA 



tained as a product from the silkworm. The silkworm 

 is not a worm, however, but one of the stages in the 

 life history of a moth. Moths are insects, and like 



Wbol fiber FUx fiber Cotton fiber Silk Tiber 



FIG. 226. TYPES OF FIBERS 



butterflies they pass through four stages (egg, larva 

 or caterpillar, pupa, and adult) before their lives are 

 completed. 



The raising of silkworms has been carried on in 

 China since 3000 B.C. Silkworm eggs that develop 

 into young caterpillars (the larva stage) are collected. 

 These caterpillars feed on mulberry leaves, grow 

 rapidly, and then spin cocoons around their bodies. 

 The cocoon acts as a protective covering during the 

 change from the caterpillar stage to the adult stage. 

 This is called the pupa stage. The pupae are killed by 

 placing the cocoons in hot water. Then the cocoons 



;ire dried and the silk fibers reeled from them. This raw 

 silk is sent to factories where it is treated with various 

 chemicals and woven by machinery into different 

 styles of fabrics which are sold to us as silk, georgette, 

 satin, velvet, etc. 



Nearly three thousand silkworm cocoons are re- 

 quired to produce a pound of raw silk. Since most of 

 the labor in the production of the reeled silk is done 

 by hand, silkworm raising is confined largely to na- 

 tions like India, Japan, and China, where labor is 

 cheap. 



Marked progress has been made in recent years 

 in man's attempt to imitate nature's processes. Arti- 

 ficial silk or rayon is made from cellulose obtained 







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International News Photos, Inc. 



FIG. 227. SILKWORMS AT WORK 



principally from cotton or wood. Cellulose is dissolved 

 in a chemical substance and then forced through small 

 openings into some solution in which it is insoluble. 

 Fine filaments, shaped like a tube and regular in out- 

 line, are formed from this treatment. 



In some respects rayon is more desirable than 

 natural silk. It possesses a greater luster than natural 

 silk and takes direct cotton dyes readily, with the pro- 

 duction of rich shades of color. It is also only about 

 one-third as expensive as real silk. Its chief disadvan- 

 tage is that it is not as strong as real silk. Rayon fibers 

 show a decided weakness when wet ; therefore great 

 care must be exercised when washing them, otherwise 

 the fibers will be broken. Methods of improving the 

 strength of rayon have been found which have re- 

 sulted in considerable improvement in this respect. 



How is clothing kept clean? It is important, for at 

 least two reasons, that we keep our clothing clean. 

 First, clean, neat clothing gives us a more attractive 

 appearance. All of us are judged to some extent by 

 our personal appearance. Second, it is more healthful 



