Manual of chemical analysis as applied to the examination of medicinal chemicals : a guide for the determination of their identity and quality, and for the determination of their identity and quality, and for the detection of impurities and adulterations : for the use of pharmaceutists, physicians, druggists, and manufacturing chemists, and of pharmaceutical and medical students . Stearic acid may be detected in the above-described alco-holic solution, by adding an equal volume of water ; the liquidbecomes turbid, but, on warming it gently, by dipping the test-tube in hot water, it becomes tra
Manual of chemical analysis as applied to the examination of medicinal chemicals : a guide for the determination of their identity and quality, and for the determination of their identity and quality, and for the detection of impurities and adulterations : for the use of pharmaceutists, physicians, druggists, and manufacturing chemists, and of pharmaceutical and medical students . Stearic acid may be detected in the above-described alco-holic solution, by adding an equal volume of water ; the liquidbecomes turbid, but, on warming it gently, by dipping the test-tube in hot water, it becomes transparent again ; the appear-ance of an oily layer on the surface would indicate tlie abovefatty acid. Salicin, sugar^ and mannite^ i^^-Jbe detected in the solution of thepreceding test, if free from fatty sub-stances, by mixing it, in a porcelaincapsule, with about fiYQ grains ofbarium carbonate, and evaporatingthe whole to dryness with constantstirring ; the residue is trituratedwith a little water, and transferredupon a moist filter ; the obtainedfiltrate is evaporated at a gentleheat, upon a watch-glass, and mustleave no residue, or only a verysmall one ; if a residue remains, itis divided, and placed upon twowatch-glasses, with one drop of wa-ter upon each, and is again dried up at a gentle heat; then,upon the one glass, a small drop of concentrated sulphuric acid 21. Fig. 83. 322 MANUAL OF CHEMICAL ANALYSIS. is allowed to fall from a glass rod or from a small pipette (); a red color will be produced if salicin is present, a blackone if sugar I maimite remains unchanged, and may be de-tected on the second watch-glass, by a few drops of alcohol,which dissolve the mannite, and leave it behind in small, acicu-lar crystals upon spontaneous evaporation. Since quinia sulphate dissolves without apparent changein strong sulphuric acid, even when gently warmed, this testmay be directly applied for the detection of admixtures ofsugar, mannite, or fatty acids, which will produce
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