IV. ARROW-ROOT. The term of arrow-root is usually applied to almost every farina bearing any resemblance to, the true or Maranta arrow-root; each packet is generally labelled with the name of the place from which it is obtained; thus, there are the West Indian, Jamaica, Demerara, Bermuda, St. Vincent, East Indian, Brazilian, African, Guinea, Sierra Leone, Portland, British, and a variety of others; a great objection to this nomenclature, arises from the fact that several different names often apply to the same kind of arrow-root. Dr. Hassall proposes to name them according to their species: these are Maranta, Curcuma, Tacca, Arum, Manihot, Potato arrow-root, &c. In every case, the part of the plant constituting the commercial arrow-root, is the starch, and is extracted by crushing the starchy part of the plant, washing it with water, and allowing the particles in suspension to subside; these particles form a thick deposit, which, being dried, assumes the form of arrow-root. 1. Maranta, called commonly West India arrow-root.Its colour, when pure, is a dull and opaque white; if pressed between the fingers it crepitates, and when treated with about twice its weight of concentrated hydrochloric acid, it should yield an opaque paste becoming transparent after a few minutes. Under the microscope, the starch corpuscles (woodcut, see p. 15) of arrow-root are seen to have an ovate and sometimes mussel-shape form; they exhibit a distinct mark, usually placed at their broadest end, and which may be either triangular or stellated; in some cases it is reduced to a single line. The corpuscle is, moreover, surrounded by concentric rings. 2. Curcuma, or East India, arrow-root is distinguished from the latter by the size and form of the granules, the position of the sharp line, and the incomplete rings seen on the surface of the corpuscles. 3. Tacca oceanica, Tacca arrow-root, or Tahiti arrowroot. Its granules resemble somewhat those of sago meal, but are very much smaller; when seen endways, they exhibit a circular and occasionally an angular or polyhedral form; when viewed sideways, they appear to have truncated bases. 4. The Arum arrow-root is obtained from the tubers of the Arum maculatum; it is chiefly prepared in Portland Island, hence it is generally called Portland arrow-root. Its starch granules are very small, and, except in size, they resemble very closely those of Tacca arrow-root. 5. The Manihot arrow-root, or Tapioca, the starch of the Manihot utilissima, is sometimes imported into this country under the name of Brazilian arrow-root. The starch granules of tapioca resemble those of Tacca arrow-root, but are considerably smaller, with a larger proportion of granules which exhibit a circular outline in the field of the microscope; the hilum or mark is usually fissured. 6. Potato arrow-root, or Potato starch.-See potato flour (woodcut, p. 15). Adulterations of arrow-root. 1. With potato flour, (p. 15). In this case, the potato flour may form the largest portion of the article. 2. With Sago starch (p. 15), or Tapioca.-These, with potato flour, have been observed, by the Commission of the 'Lancet', as the only adulteration of Maranta arrow-root. Out of fifty samples of arrow-root submitted to analysis by the Commission, twenty-two were found adulterated. In ten samples the adulteration was carried to such an extent, that they contained scarcely a particle of genuine Maranta or West Indian arrow-root, for which they were sold. One consisted almost entirely of Sago meal; two of Potato flour and Sago meal; two of Tapioca, Sago meal, and Starch; one of Tapioca starch; and four were composed entirely of Potato arrow-root. V. REVALENTA Consists of the starch of French lentils, and probably mixed with Indian corn meal (p. 15). A Cellular structure of inside substance. B. Structure of outer membrane. VI. SEMOLINA Consists of wheat gluten, with a certain proportion of starch. VII. SUGAR; AND ITS ADULTERATIONS. There are two different kinds of sugar met with in commerce-1st, cane sugar; and 2d, grape sugar; the first being obtained from the sugar cane, the maple, beetroot, and some other plants; and the second prepared from grapes and figs; it can also be obtained by a chemical process, i. e., from the action of dilute mineral acids on starch or woody fibre. Grape sugar is frequently found in the brown sugars of commerce in considerable quantity, and is sometimes introduced therein for purpose of adulteration. Tests.-1. Cane sugar crystallizes in a prismatic form, does not deliquesce when pure, if exposed to moisture. Its solution gives no immediate precipitate, when boiled with a solution of sulphate of copper and an excess of potash. It is very sparingly soluble in alcohol. 2. Grape sugar does not crystallize readily; is very apt to deliquesce, especially when kept in a damp place, and has usually a dark brown colour; its taste is not so sweet as that of the cane sugar; it is peculiarly cooling to the mouth. Its solution, when heated with the copper test (see page 9), yields a precipitate of an orange colour, appearing just as the fluid is about to boil. It is soluble in alcohol. (See article on Alcoholic Beverages.) I have had an opportunity of examining a few of the most important kinds of cane sugar, and the reader will notice in the following report that in general the whiter the quality the less water it contained. 1. Java sugar.-White, with a tinge of brown; rather small-grained; crystals appear dry, and have a light structure. Three grammes contain 0.007 grammes of water, or 100 parts of sugar yield 0.233 of moisture. 2. Havannah sugar has a slightly darker brown colour; crystals not so well formed; grains of the same size as those of Java sugar; appears dry. Three grammes yield 0.037 grammes of water, or 100 parts of sugar contain 1.233 of moisture. 3. Sugar of Brazil.-Rather darker coloured than Havannah sugar; crystals of the same size, but of a somewhat heavier structure, and slightly damp. yield 0.082 of water, or 100 parts contain Three grammes Three 2.733. 4. Sugar of Bengal (Benares).-More coloured and damper than the last; crystals much finer. Three grammes yield 0.110 of water, or 100 parts contain 3.666 of moisture. 5. Sugar of Mauritius.-Brown coloured and damp; crystals large. Three grammes yield 0.115 of moisture, or 100 parts contain 3.833 parts of water. 6. Sugar of Cuba.-Same colour as preceding; grain smaller; appears damp. Three grammes yield 0·094 of moisture, or 100 parts contain 3.133 of water. 7. Sugar of Madras.-Dark brown colour; grain very small, very heavy, and wet. Three grammes yield 0·269 grammes of moisture, or 100 parts contain 8.966 parts of water. IMPURITIES OF CANE SUGAR. Dr. Hassall divides them into organic and inorganic; for the sake of practical utility, I propose to classify them according to the methods employed for their detec tion. 1. Mechanical impurities, or those which do not dissolve in a solution of sugar, and can be seen with the microscope, as fragments of cane sugar, blood, an animalcule peculiar to sugar, fungi, woody fibres, starch globules, sporules of fungi, carbonate of lime, and sand. 2. Chemical impurities, or those dissolving in a solution of sugar, and in this form escaping the scrutiny of the microscope, which are grape sugar or glucose, and vegetable albumen. |