The analysis and adulteration of foods / by James Bell.

  • James Bell
Date:
1881-1883
Catalogue details

Licence: Public Domain Mark

Credit: The analysis and adulteration of foods / by James Bell. Source: Wellcome Collection.

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    and whey ; but this information remained for many centuries -nearly all that was known regarding it. It is only during comparatively recent years that the composition and properties of the several characteristic substances found in milk have been fully investigated, and their proportions in the various kinds of milks accurately estimated. CHEMICAL COMPOSITION. When milk is allowed to stand for some time the cream rises to the surface. If this be removed, the remaining liquid will after a further period spontaneously separate into a solid portion called curd, and a liquid called whey or serum, which is essentially an aqueous solution of milk-sugar. By a sort of natural analysis we thus find that milk is divisible into Crea7u, Curd, and a watery solution of milk-sugar with a little mineral matter. The following table contains the results of the analyses of five samples of milk : Table I.—Constituents of Cow’s Milk. No. I. No. 2. No. 3. No. 4. No. 5. Specific Gravity Total Solids Non-fatty Solids 1031-56 11-47 8-71 1031-56 11-09 8-66 1031-00 11-98 8-65 1032-50 12-79 9-03 1029-80 15*89 9-10 Fatty percentage ... Casein ,, Sugar ,, Ash Water ,, 2-76 3’05 4-91 075 88-53 2-43 2-96 4-96 0-74 88-91 3*33 3*i8 475 ■ 0-72 88-02 376 3*50 475 0-78 87-21 6-79 3*31 5*07 0-72 84-11 Total 100-00 100-00 100-00 100-00 100-00 —This, in a somewhat impure state, owing to the presence of curd and milk-sugar, constitutes butter. Whilst present in the milk the fat exists in the form of globules suspended in the liquid. It has been debated whether these globules have an envelope or B 2
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