II.—Schweitzer’s reagent for textile fibers and cellulose is made by dissolving 10 parts of copper sulphate in 100 parts of water and adding a solution of 5 parts of potassium hydrate in 50 parts of water; then wash the precipitate and dissolve in 20 per cent ammonia until saturated. This solution dissolves cotton, linen, and silk, but not wool. The reagent is said to be especially useful in microscopy, as it rapidly dissolves cellulose, but has no action on lignin.
III.—Jandrier’s Test for Cotton in Woolen Fabrics.—Wash the sample of fabric and treat with sulphuric acid (20 Bé.) for half an hour on the water bath. To 100 to 200 parts of this solution add 1 part resorcin, and overlay on concentrated sulphuric acid free from nitrous products. The heat developed is sufficient to give a color at the contact point of the liquids, but intensity of color may be increased by slightly heating. If the product resulting from treating the cotton is made up 1 in 1,000, resorcin will give an orange color; alphanaphtol a purple; gallic acid a green gradually becoming violet down in the acid; hydroquinone or pyrogallol a brown; morphine or codeine, a lavender; thymol or menthol a pink. Cotton may be detected in colored goods, using boneblack to decolorize the solution, if necessary.
IV.—Overbeck’s test for cotton in woolen consists in soaking the fabric in an aqueous solution of alloxantine (1 in 10), and after drying expose to ammonia vapor and rinse in water. Woolen material is colored crimson, cotton remains blue.
V.—Liebermann’s Test.—Dye the fabric for half an hour in fuchsine solution rendered light yellow by caustic soda solution and then washed with water—silk is colored dark red; wool, light red; flax, pink; and cotton remains colorless.
To Distinguish Cotton from Linen.—Take a sample about an inch and a half square of the cloth to be tested and plunge it into a tepid alcoholic solution of cyanine. After the coloring matter has been absorbed by the fiber, rinse it in water and then plunge into dilute sulphuric acid. If it is of cotton the sample will be almost completely bleached, while linen preserves the blue color almost unchanged. If the sample be then plunged in ammonia, the blue will be strongly reinforced.
Aromatic Cotton.
Cotton Degreasing.
COTTONSEED HULLS AS STOCK FOOD.
Cottonseed hulls or other material containing fiber difficult of digestion are thoroughly mixed with about 5 per cent of their weight of hydrochloric acid (specific gravity, 1.16), and heated in a closed vessel, provided with a stirrer, to a temperature of 212° to 300° F. The amount of acid to be added depends on the material employed and on the duration of the heating. By heating for 30 minutes the above percentage of acid is required, but the quantity may be reduced if the heating is prolonged. After heating, the substance is ground and at the same time mixed with some basic substances such as sodium carbonate, chalk, cottonseed kernel meal, etc., to neutralize the acid. During the heating, the acid vapors coming from the mixture may be led into a second quantity of material contained in a separate vessel, air being drawn through both vessels to facilitate the removal of the acid vapors.
COTTONSEED OIL: See Oil.