Mechanical Impurities. Chemical Impurities. Fragments of Microscopical examination-Cells and bundles of woody fibres. Sugar-Cane Chemical examination-(Not required). Blood Animalcules Woody Fibres Starch Glo bules Sporules of Microscopical examination-Small round globules, of a yellowish colour. Chemical examination-A scum or coagulumn appears when the solution is boiled. It is very apt to turn acid when left in a warm place. Microscopical examination-The sugar insect. (See the woodcut.) Chemical examination-Ammonia is evolved from the pre- Microscopical examination-Fibres (of the fir) exhibiting }(See "Flour and its Adulterations.”) Microscopical examination-Minute bodies of an oval form, becoming developed into fungi when the solution is left in a warm place. Chemical examination-Solution of sugar ferments, and turns acid very readily. Microscopical examination-Light amorphous particles. floating on the solution. Carbonate of Chemical examination-Dissolved with the evolution of Lime Sand Grape Sugar Vegetable Albumen carbonic acid, when mixed with hydrochloric acid on the microscope glass. Microscopical examination-Small bodies, having a sharp angular structure. Chemical examination-Insoluble in dilute hydrochloric acid. (See also page 20.) Chemical examination-Yields a red precipitate with the copper test. For rough quantitative analysis, treat the sugar with alchohol, evaporate to dryness, and weigh the residue. Chemical examination-An amorphous deposit appearing when the solution is boiled, and insoluble in nitric acid. 1 For the application of this test, let the solution of sugar be filtered; dry the filter, and eut it into small pieces; then mix it with lime; introduce the mixture into a test tube and heat; if any ammonia be given out, a piece of paper, moistened with a solution of sulphate of copper, will turn deep blue when placed before the opening of the test tube. If the solution of sugar should contain vegetable albumen, it will be necessary to wash the filter with cold water, until a sample of the filtrate evolves no more ammonia when boiled with lime. Sporules of fungi also contain a little nitrogen, but in so small a proportion that I do not think it could be easily detected by the method just described. Most of the brown sugars imported into this country are subject to these impurities, and may be seen with the microscope to contain fragments of cane, woody fibres and grit, occasionally acari, and sporules of fungi. Sugars of this kind are imperfectly crystallized, small-grained, often presenting an earthy appearance, damp and heavy. White or pure sugar is light-coloured, highly crystalline, and very dry. Adulterations of sugar.-Sugar may be adulterated with impure and small-grained sugar, with flour, potato sugar or glucose, gum or dextrine, and finally with water, lead, and iron. 1. The inferior kinds of sugar are liable to be adulterated by the addition of a still more impure quality, and other inferior kinds of small-grained sugar; a close examination with the naked eye will suffice in many cases to detect the fraud. 2. To determine the presence of flour in sugar, let a sample of the sugar be dissolved in water, and the insoluble residue examined with the microscope (see p. 15). 3. To detect the adulteration of cane sugar with potato sugar or glucose, employ the same process as that given for the detection of grape sugar in impure cane sugar (see pp. 36 and 38). 4. The gum or dextrine used to adulterate sugar is prepared from potato flour by subjecting it to a fixed temperature for a certain time; in this case a microscopical observation will often reveal the presence of fragments of starch corpuscles, and the addition of acetate of lead to a solution of the sugar will produce a bulky precipitate. 5. When cane sugar is artificially moistened with water, the paper in which the sugar has been wrapped up, is often wetted and stained, thereby indicating the adulteration; as a further proof, dry in the water bath a weighed sample of the suspected sugar, ascertain its weight when dry, and the difference will show the quantity of water it contained. 6. Lead (acetate of) and iron are but seldom used to adulterate sugar. To detect lead, add iodide of potassium to the solution, and observe whether a yellow precipitate of iodide of lead be obtained. Iron is precipitated by treating the solution with ammonia; the precipitate has a reddish-brown colour. HOW ARTICLES OF CONFECTIONARY ARE COLOURED AND POISONED. The following colours are employed in confectionary: I. RED OR PINK.-Vegetable: Solution of cochineal or Coccus lacti.-Test: Immerse a small portion of the comfit in caustic potash, and another in acetic acid; it will become purplish in the alkaline, and red in the acid solution. : Mineral: Red lead, red oxide, or bichromate of lead.Test Burn the comfit, dissolve the ashes in a few drops of nitric acid, and dilute the solution; sulphuretted hydrogen added to it occasions a black, and iodide of potassium a yellow precipitate. If chromate of lead be present, the ashes will produce, with borax, a green bead in the blowpipe flame. Vermilion, or bisulphuret of mercury.-Test: Incinerate the comfit, and introduce the ashes with a little caustic soda, into a test-tube;1 on the application of heat, metallic mercury will be deposited on the cold upper part of the tube, if any vermilion be present. II. YELLOW.-Vegetable: Gamboge.-Test: Dissolve the comfit if possible in water; the presence of gamboge will occasion an emulsion; evaporate it to dryness, treat the residue with alcohol, and mix the solution with water, to precipitate the yellow gamboge. Ammonia, when added to the fluid, dissolves the last-mentioned precipitate, producing a blood-red colour; the addition of nitric acid to this solution yields a pale yellow precipitate. Turmeric.-Test: Does not form so decided an emul 1 It is better to pound the comfit, treat it with water, and filter; the filter is to be dried at a low temperature, cut into small pieces, and introduced inside a test tube with a little caustic soda. sion with water as gamboge; much care is requisite to discriminate between the two. Mineral: Chromate of lead.-Test: In some cases sulphuretted hydrogen applied to the comfit turns it black or brown; try also the tests recommended for the detection. of red lead and bichromate of lead (red) (see p. 41). Naples yellow, or a mixture of lead and antimony.-Test: Incinerate in a test-tube; antimony volatilizes, and is deposited in the metallic form in the cold part of the tube; this bright ring is insoluble in liquor soda chlorinatæ. Test for lead as above. III. BLUE.-Vegetable: Litmus.-Test: Becomes red by the action of a weak acid on a solution of the comfit. Indigo.-Test: Sublimes in dense violet vapours when the article of confectionary is burnt. Mineral: Prussian blue.--Test: Comfit immediately discoloured when immersed in caustic alkalies. Antwerp blue, or Prussian blue made lighter by the addition of some colourless substance.-Test: The same as above. The two verditers: 1st, carbonate of copper; 2d, carbonate of copper made lighter by the addition of lime.1—Test : Insoluble in water; soluble in sulphuric acid, with evolution of carbonic acid; ammonia added to this solution produces a blue colour. The pale verditer is not entirely soluble in sulphuric acid, the residue containing sulphate of lime (see p. 19.) Cobalt.-Test: Incinerate the comfit, dissolve the ashes in nitric acid, and add a few drops of the solution to a little 1 Pound the comfit, or a sample of its coloured sugar, exhaust it with distilled water, and the insoluble residue, if it consist of one of the verditers, will be found to possess the above characters. |