Air, water and food from a sanitary standpoint . by means of the Westphal balance (see Allen, TheAmlyst, II, 223; also Bull 13, Part IV, pp. 430-431). Thepyknometer method is, however, the one adopted by the As-sociation of Official Agricultural Ghemists, to whose report(Bulletin 46, Rev. Ed., 1899, p. 51) reference is made. Melting-point.—This is best determined according to thedirections given in the Bulletin just mentioned (46), p. 52. Refractive Index.—The degree to which light is refracteddiffers with various fats, and these differences are often ofconsiderable analytical value. See Bulle
Air, water and food from a sanitary standpoint . by means of the Westphal balance (see Allen, TheAmlyst, II, 223; also Bull 13, Part IV, pp. 430-431). Thepyknometer method is, however, the one adopted by the As-sociation of Official Agricultural Ghemists, to whose report(Bulletin 46, Rev. Ed., 1899, p. 51) reference is made. Melting-point.—This is best determined according to thedirections given in the Bulletin just mentioned (46), p. 52. Refractive Index.—The degree to which light is refracteddiffers with various fats, and these differences are often ofconsiderable analytical value. See Bulletin 46, Rev. Ed., , for a description of the method employed in its determina-tion. Determination of Water. — Directions. — Weigh 2grams of butter into a shallow platinum dish having a flatbottom two inches in diameter and containing a slender stir-ring-rod two and a half inches long. Heat the butter in theoven at 100° C. for thirty minutes, cool in a desiccator, and * From photomicrographs by A. G. Woodman and A. I. Kendall, A. Kuter X 30. C. Oleomargarine X 30. K. Reef-fat X 3cU. Lard X 30. food: analytical methods: butter. i8r weigh. Heat again for periods of fifteen minutes, until theweight remains constant. During the process of heatingstir the butter frequently to hasten evaporation of the water. ]S[ote.—The loss in weight is calculated as water, althougha portion of the volatile acids is also lost, the amount depend-ing upon the time of heating. Determination of Salt.—Directions.—Weigh lo grams of butter in a small beaker, add 30 of hot water, and when the fat is completely melted transfer the whole to a separatory funnel. Shake the mixture thoroughly, allow the fat to rise to the top, and draw off the water, taking care that none of the fat-globules pass the stopcock. Repeat the operation four times, using 30 of water each time. Make the washings up to 250 , mix thoroughly, and titrate 25 in a six-inch porcelain dish, using
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