If the student require more precise knowledge of the nature of a fibrous material than that afforded by a determination of the cellulose, the following method of analysis will prove of service.
About two grms. are taken and dried at 110–115° C. until the weight remains constant: the loss represents water. The fibre is then treated with a hot mixture of benzene and alcohol, dried as before and weighed: the loss is fat, wax, {45} &c. The residue from this treatment is then repeatedly exhausted with boiling water and again dried at 110–115° C. and weighed: the loss is put down as aqueous extract. The exhausted fibre is then treated for cellulose by either of the methods given on p. [19]. The ash is determined in a separate portion.
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CHAPTER IV. AN ACCOUNT OF THE CHEMICAL AND PHYSICAL CHARACTERISTICS OF THE PRINCIPAL RAW MATERIALS.
This chapter contains the results obtained from an investigation of the different plant fibres by the methods indicated in the two previous chapters.
In the following table the fibres are classified according to the reactions which they give with iodine solution.
| A. Seed Hairs. | B. Dicotyledonous Bast Fibres. | C. Monocotyledonous Fibres corresponding to Bast Fibres. | |
|---|---|---|---|
| Blue reaction | Cotton. | Linen. | Straw. |
| Hemp. | Esparto. | ||
| China grass. | Pine apple. | ||
| Paper mulberry | |||
| Sunn. | |||
| Yellow reaction | Jute. | New Zealand flax. | |
| Yucca. | |||
| Hibiscus. | Aloe. | ||
| Manilla hemp. |
Class A. COTTON.
Microscopic features.—Fibres simple, opaque, flattened, always more or less twisted upon itself, side wall membranous, showing striæ. {47}
Sections.—Simple, oval, irregular, central cavity often containing granules.