260 Plant Biology 



As illumlnants, the fixed, nondrying oils serve best. Illuminating oils 

 must volatilize but not too quickly; they must be inflammable but not 

 dangerous or explosive. Among the illuminating oils are crude oils, 

 kerosene, olive oil, peanut oil, rape oil, etc. 



Plant Fibers. — Plants which produce fibers have contributed greatly 

 to the advancement of civilization, and plants providing foods have 

 been the most useful of all plants. 



Plant fibers as well as animal fibers and skins have been utilized since 

 prehistoric times for clothing, baskets, fish lines, bowstrings, snares, nets, 

 etc. More recently such materials have been utilized for making brushes, 

 paper, cellulose products, cordage, mattings, wickerwork, fabrics, pack- 

 ings, awnings, tapes, laces, straw hats, etc. 



Cotton fibers cover the seeds of several species of cotton plants. These 

 fibers are separated from the seeds by the machine known as the cotton 

 gin. These fibers are then cleaned, combed, and spun into threads. The 

 latter are woven into fabrics. The cleaned cotton fibers, when rolled 

 into sheets, are known as cotton batting. The cotton fibers in the raw 

 state are more or less covered with an oil which repels water. When 

 this oil is removed, the end product is known as absorbent cotton. Ab- 

 sorbent cotton plus nitric acid plus sulfuric acid produces nitrocellulose 

 (guncotton). Nitrocellulose dissolved in alcohol and ether forms col- 

 lodion. Collodion when forced through fine openings into running 

 water hardens into silklike fibers. 



Flax fibers are practically pure cellulose which is obtained from the 

 stems of the flax plant by a process of retting or rotting. These fibers 

 are strong and fine and are used widely in making fine lace, linen, duck, 

 canvas, and better qualities of paper. The retting process is a decom- 

 position process due to the action of certain species of bacteria. 



Hemp fibers, secured from the hemp plant, are coarser, longer, and 

 stronger than flax and are used in making rope, twine, sailcloth, bags, 

 and similar coarse fabrics. 



Jute fibers are obtained from plants (linden family) closely related to 

 flax, but the fibers are not so strong or durable and contain less cellulose. 

 They are used in making burlap, bags, and similar coarse fabrics. 



Manila hemp fibers are coarse and fine fibers obtained from the edge 

 of the fleshy leaf stalks of the Manila hemp plant (banana family). 

 The principal source is from the Philippine Islands. The fibers are 

 much stronger than those of ordinary hemp and are used in making 

 bags, mats, sailcloth, Manila paper, and similar materials. 



