OILCLOTH 



4357 



OJIBWA 



OILCLOTH, a heavy ornamental cloth, some- 

 times called floorcloth, used commonly to 

 cover wood that requires frequent washing. 

 Its foundation is a strong, coarse burlap, made 

 of flax and hemp, which is stretched in a frame, 

 brushed with a glue-size made of glue, rye 

 flour, tobacco and varnish, then dried and 

 rubbed with pumice stone. Two or three coats 

 of thick, heavy paint are then applied, and 

 each coat, when dry, is smoothed with pumice 

 >tone. After this process, the cloth is placed 

 in a loom where the pattern is printed by 

 blocks, as in calico printing, each color having 



a block. 



Floor oilcloth is manufactured in many 

 grades, and measures from three feet to twenty- 

 four feet in width. It has largely been su- 

 perseded by linoleum, as the latter contains 

 a mixture of ground cork and oxidized linseed 

 oil which makes it more durable. Lighter 

 weights of oilcloth are used for tables, pantries 

 and various household purposes. See LINO- 

 LEUM. 



OILS, a class of substances composed chiefly 

 of hydrogen and carbon, which in a liquid state 

 flow slowly and adhere to most substances with 

 which they come in contact. Oils are lighter 

 than water, and will not dissolve in it, but 

 they are soluble in alcohol and a few other 

 substances. According to the sources from 

 which they are obtained, oils are classified as 

 animal, vegetable and mineral; according to 

 their behavior on heating they are classified 

 as fixed (or fatty) and volatile. 



Fixed Oils. Fixed oils are of both animal and 

 vegetable origin. Those obtained from animal 

 tissue are extracted by pressing the tissue when 

 cold, and by heat and pressure. Since a much 

 larger quantity of oil is obtained by the use 

 of heat, this method is usually employed. 

 Among the most valuable fixed oils are those 

 obtained from certain kinds of fish, as, men- 

 haden, salmon, sardine, herring and sturgeon. 

 These are sometimes known as marine, or fish, 

 The seeds of certain plants are also im- 

 portant sources of fixed oils. Chief among 

 'them are flaxseed, from which linseed oil is 

 obtained; cotton seed, corn and sesame. Tin 

 ml is obtained by grinding tin- seed and sub- 

 jecting the product to great pressure cither 

 with or without heat. The oil obtained with- 

 out heat is of better quality than that obtained 

 by raising the crushed seed to a high tempera- 

 . and it is usually designated as cold- 

 pressed. Castor oil used in medicine is a good 

 example. Heat is usually employed in the ex- 



traction of vegetable as well as of animal fixed 

 oils, because by its use larger quantities are 

 obtained. Fixed oils are liquid fats and some 

 of them are solid at ordinary temperatures. 

 The fish oils, olive oil and linseed oil are 

 good examples of those that are l*quid at 

 ordinary temperatures. 



Drying Oils are those that absorb oxygen 

 when exposed to the air and form an elastic 

 solid substance when spread in thin coats. 

 These oils are extensively used in making 

 paints, the most important among them being 

 linseed, hemp, walnut, poppy, candle-nut, ses- 

 ame, sunflower and Chinese wood oils. 

 drying oils on exposure to the air ferment and 

 become rancid. Olive, cottonseed and almond 

 oils are good examples. Semidrying oils ab- 

 sorb oxygen from the air rapidly but do not 

 harden. Oil-soaked rags sometimes absorb 

 oxygen so rapidly that they take fire from the 

 heat developed by the chemical action. Croton- 

 and grape-seed oils are good examples of semi- 

 drying oils. Fixed oils are lighter than v, 

 and will not dissolve in it. They dissolve read- 

 ily in alcohol and ether, and those used in 

 paints dissolve in turpentine. 



Fixed oils are used for many purposes, such 

 as food, making soap, dressing leather, making 

 paints, lubricating machinery and for illumina- 

 tion. See FAT; LINSEED OIL; PAINT. 



Volatile Oils. Volatile oils are thoso that 

 evaporate rapidly on exposure to the air. They 

 are obtained from plants, and are usually ex- 

 tracted by distilling the plant or some part of 

 it with water. The more delicate oils, like the 

 oil of rose, are often obtained by packing the 

 flowers in such a fat as lard, which absorbs the 

 oil. The fat is then heated and the oil sepa- 

 rated from it by distillation. When dissolved 

 in alcohol volatile oils form essences. They 

 are extensively used in the manufacture of 

 perfumery, and some of them, as peppermint, 

 clove and wintergreen, are valuable in m<.l- 

 cine. The oils of clove, rosemary, cinnamon, 

 lemon, lime, orange and nutmeg are used in 

 the arts. See PERFUME. c.ii.n 



OJIBWA, o jib' way, one of the most peace- 

 able tribes of the North American Indians, 

 belonging to the Algonquian stock. Form 

 they occupied large tracts of land about tin- 

 upper Great Lakes, in Michigan. Minnesota, 

 Ontario, Manitoba and neighboring regions, 

 and now d.vrll upon reservations in the same 

 districts. Their Indian name, Chipwayanwok, 

 means taihkin*, and was p; u on ac- 



count of their dress, which had points hang mi: 



