Tham khảo tài liệu 'materials handbook 15th ed - g. brady_ h. clauser_ j. vaccari (mcgraw-hill_ 2002) episode 3', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 160 CANNEL COAL 45 to 65. The refined grade is purified by remelting and contains not more than about 1 water. It is soluble in turpentine and is used for varnishes polishes and leather finishes as a substitute for carnauba wax or to blend with carnauba or beeswax. About half the production goes into furniture and show polishes but it does not have the selfpolishing characteristics of carnauba wax. It is also used in electrical insulators candles and sound records. CANNEL COAL. A variety of coal having some of the characteristics of petroleum valued chiefly for its quick-firing qualities. It consists of coallike matter intimately mixed with clay and shale often containing fossil fishes and probably derived from vegetable matter in lakes. It is compact in texture dull black and breaks along joints often having an appearance similar to black shale. It burns with a long luminous smoky flame from which it derives its old English name meaning candle. On distillation cannel coal yields a high proportion of illuminating gas up to 16 000 ft3 ton 450 m3 ton leaving a residue consisting mostly of ash. At low temperatures it yields a high percentage of tar oils. The proportion of volatile matter may be as high as 70 . It is found in Great Britain and in Kentucky Ohio and Indiana. Cannel coal from Scotland was originally called parrot coal and boghead coal was a streaky variety. CARBOHYDRATES. The most abundant class of organic compounds constituting about three-fourths of the dry weight of the plant world. They are distinguished by the fact that they contain the elements carbon hydrogen and oxygen and no others. Many chemical compounds such as alcohols and aldehydes also have these elements only but the term carbohydrate refers only to the starches sugars and cellulose which are more properly called saccharides. Their properties vary enormously. Sugars are soluble crystalline and sweet starches form pastes and are colloidal celluloses are insoluble. They are best known for .
