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 . any flavors indicative of a previous employment ofthe alcohol for the extraction of vegetable substances. Methyl Alcohol.—Among the several methods for the detec-tion of methylic alcohol as an admixture in ethyl alco
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 . any flavors indicative of a previous employment ofthe alcohol for the extraction of vegetable substances. Methyl Alcohol.—Among the several methods for the detec-tion of methylic alcohol as an admixture in ethyl alcohol, thefollowing is least open to objection : Thirty grains of powderedpotassium bichromate are dissolved, in a little flask, in half anounce of water; 25 drops of concentrated sulphuric acid, and ALCOHOL. 121 subsequently 40 drops of the alcohol under examination, areadded, and the flask closed with a cork provided with a deliv-ery-tube, leading into a large test-tube, cooled in ice-water (). After allowing the mixture to stand for about a quarterof an hour, the flask is gently warmed until about half a fluid-ounce of distillate is obtained; the distillate is then slightlyover-saturated with a little crystallized sodium carbonate, andevaporated to the bulk of about one-quarter of an ounce ; whencool, it is filtered into a small test-tube, and then slightly over-. TiG. 42. saturated with a few drops of acetic acid; 20 drops of solutionof argentic nitrate (1:20) are then added, and the mixturegently heated for a few minutes. If tlie liquid merely darkensa little, but continues quite translucent, the alcohol is free frommethylic alcohol; but, if a dark-brown or black precipitate ofreduced silver separates, and the test-tube, after being rinsedand filled with water, shows upon its interior a brilliant metal-lic resplendence, which, when seen against white paper, ap-pears brown by transmitted light, the alcohol is methylated. 122 MANUAL OF. CHEMICAL ANALYSIS. ALCOHOL AMYIi
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