naphtha, is also dissolved by ether, and can be estimated by digesting another portion of the sample with water, and titrating the filtered liquid with decinormal soda solution. Its weight is then to be deducted from the amount of fat previously obtained, in case ether was employed in this determination. The relative proportions of the soluble and insoluble fatty acids contained in cheese possess the same significance in indicating the presence of oleomargarine and other foreign fats as with butter; and they are determined by the same methods. The examination of the colouring matter of cheese can be made by first neutralising the free lactic acid, separating the fat by agitation with water, filtering and drying; the fat is then tested with carbon disulphide and potassium hydroxide (see p. 77). FOOTNOTES: [47] ‘Analyst,’ Jan. 1885, p. 3. [48] Chem. News, pp. 47, 85. [49] Dingl., vol. i. pp. 247, 474. FLOUR AND BREAD. Wheat (_Triticum vulgare_) forms the principal bread-stuff of civilized nations, and is by far the most important of all cereal grasses. It has one or more slender, erect and smooth stalks, which, owing to the large proportion of siliceous matter present, possesses the strength necessary for the support of the ears. The grain is imbricated in four rows. The following are the averages of the results obtained by the analyses of 260 samples of American wheat, made by the United States Department of Agriculture, in 1883:-- Per cent. Water 10·27 Ash 1·84 Oil 2·16 Carbohydrates 71·98 Fibrin 1·80 Albuminoids 11·95 Nitrogen 1·91 Analyses of the ash of wheat by the same Department, furnished the following results:-- ----------------+---------+------------------- | | Foreign. | Dakota. +---------+--------- | | Winter. | Spring. ----------------+---------+---------+--------- |Per cent.|Per cent.|Per cent. Insoluble | 1·44 | 2·11 | 1·64 Phosphoric acid | 47·31 | 46·98 | 48·63 Potassa | 30·63 | 31·16 | 29·99 Magnesia | 16·09 | 11·97 | 12·09 Lime | 3·36 | 3·34 | 2·93 Soda | 1·17 | 2·25 | 1·93 Sulphuric acid | trace | 0·37 | 0·48 Chlorine | „ | 0·22 | 0·51 Ferric oxide | „ | 1·31 | 0·28 Undetermined | .. | 0·29 | 1·52 | ------ | ------ | ------ | 100·00 | 100·00 | 100·00 | | | Total ash | 1·88 | 1·97 | 2·14 ----------------+---------+---------+--------- FLOUR.