On the composition of food and how it is adulterated : with practical directions for its analysis / by W. Marcet.

  • William Marcet
Date:
1856
Catalogue details

Licence: Public Domain Mark

Credit: On the composition of food and how it is adulterated : with practical directions for its analysis / by W. Marcet. Source: Wellcome Collection.

    58/236 (page 38)
    Blood P f Microscopical examination—Cells and bundles of woody - ,u.yn„z.i,.vSOj J fibres. Sugar-Cane y^Xx^mx^^X examination—(Not required). fMicroscopical examination—Small round globules, of a I yellowish colour. \ Chemical examination—A scum or coagulum appears when ] the solution is boiled. It is very apt to turn acid when left in a warm place. fMicroscopical examination—The sugar insect. (See the j woodcut.) Chemical examination—ximmonia is evolved from the pre- sence of nitrogen when the deposit is heated with lime.^ I No coagulum on boiling the solution, unless albumen be L also present. (Microscopical examination—Fibres (of the fir) exhibiting Wood^Fibres \ externally a number of small rings or circles, (accidental) 1 Chemical examination—Transformed into grape sugar when boiled with dilute sulphuric acid. I (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. , Chemical examination—Dissolved with the evolution of 1 carbonic acid, when mixed with hydrochloric acid on the microscope glass. fMicroscopical examination—Small bodies, having a sharp angular structure. Chemical examination—Insoluble in dilute hydrochloric acid. (See also page 20.) Starch Glo- bules Sporules of Carbonate of Lime Sand L Grape Sugar ■{ 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. Vegetable J Chemical examination—An amorphous deposit appearing 1 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 cut 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 sug^r 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 propor- tion that I do not think it could be easily detected by the method just described