Laboratory manual for the detection of poisons and powerful drugsAuthorized translation of the completely rev4th German ed. . s 1820 grams Kidneys and liver grams 1365 grams Brain grams Detection of Ethyl Alcohol Ethyl alcohol distils easily with steam and consequentlymost of it will be in the first fraction. If present in sufficientquantity, it can be recognized in the distillate by its odor. Thefollowing tests should be made: I. Liebens Iodoform Test.^—Gently warm the liquid (40-50°), add a few cc. of aqueous iodo-potassium iodide solution, ora small crystal of iodine, and enough pot
Laboratory manual for the detection of poisons and powerful drugsAuthorized translation of the completely rev4th German ed. . s 1820 grams Kidneys and liver grams 1365 grams Brain grams Detection of Ethyl Alcohol Ethyl alcohol distils easily with steam and consequentlymost of it will be in the first fraction. If present in sufficientquantity, it can be recognized in the distillate by its odor. Thefollowing tests should be made: I. Liebens Iodoform Test.^—Gently warm the liquid (40-50°), add a few cc. of aqueous iodo-potassium iodide solution, ora small crystal of iodine, and enough potassium hydroxidesolution to give the liquid a distinct yellow to brownish color. ^ Pflugers Archiv, 49, 315 (1891). 2 Annalen der Chemie und Pharmazie, Supplement Band, 7, 50 DETECTION OE POISONS If alcohol is present, a yellowish white to lemon-yellow precipi-tate of iodoform will appear immediately, or as the solutioncools. If the quantity of alcohol is very small, a precipitate will form on long standing. When iodo-form is deposited slowly, the crystalsare very perfect hexagonal plates andstars (see Fig. 9).. Fig. 9.—Iodoform Crystals. Note.—This iodoform test is very delicatebut not characteristic of ethyl alcohol, sinceother primary alcohols, except methyl alcohol,and many secondary alcohols, as weU as theiroxidation products, aldehydes and ketones,give iodoform under the same ether, aceto-acetic ether, lactic acid, etc.,also give iodoform. The correct explanation of the iodoform reaction is probably the following:Iodine and potassium hydroxide form potassium hypo-iodite (KOI) by reaction(a). This compound brings about the oxidation of alcohol to acetic aldehyde(jS) and at the same time substitutes iodine for hydrogen in the latter (7). Finallytri-iodo-acetic aldehyde is decomposed by the excess of potassium hydroxide intoiodoform and potassium formate (5): (a) 2KOH + I2 = KI + H2O + KOI, ()3) + KOI = + H2O + KI,(7)
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