Researches on cellulose Volume 4 - Softcover

Inhaltsangabe

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1922 edition. Excerpt: ...of the lime-water is to break down the cellulose dextrin to isosaccharinic acid, leaving cellulose. The fact that purified cellulose is not attacked in any way by lime-water under the conditions employed (4 grams of cellulose,-4 of lime and 100 of water, boiling 18 hours) was proved, since 100 of cotton cellulose gave 100-5 after J8 hours boiling. Extending the study of the action of lime-water to hydrocelluloses prepared from wood cellulose, the effect was again to lower the copper number from 8 or 10 to below i, with a loss in weight of some 30 per cent. Calcium isosaccharinate was identified in this case also as a secondary product. Similar results were obtained with oxycelluloses of various origin. Soda celluloses are very slightly attacked by lime boil. 'Sulphite' celluloses lose up to 50 per cent, of their pentosan content and their methyl number falls considerably. The residue still contains pentosan in extremely strong combination. The authors as the result of an exhaustive research conclude that--Hydrocelluloses are mixtures of cellulose with decomposition products; the so-called cellulose dextrins being present to the extent of 24 to 36 per cent. Oxycellulose made by the action of bleaching powder consists of about 60 per cent, normal cellulose and 40 per cent, of associated oxidation products. Sulphite cellulose contains dextrins similarly removable by lime-water. The residue obtained in all these cases is a cellulose with practically no copper reducing power. We follow this interesting research with one in which criticism is directed against some of these conclusions:--ARE HYDROCELLULOSES SIMPLE SUBSTANCES? H. Ost and R. Bretschneider (Zeit. angew. Chem., 1921, 34. 422). The authors seek to controvert the statements of Schwalbe and...

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