Examination of the urine; a manual for students and practitioners . t to enter in an estimation with Ein-horns apparatus, because in thelatter no allowance is made for tem-perature, pressure, etc., as shouldbe done in all volumetric gas anal-yses. Lohnsteins instrument con-sists of a U-shaped tube with a longarm, and another ending in a is poured into this bulb upto the zero mark on the scale of thelong arm. A definite quantity ofurine is poured over the mercury, alittle yeast is added, and the appa-ratus is closed with a glass stoppergreased in vaselin. The stopper isweighted wit
Examination of the urine; a manual for students and practitioners . t to enter in an estimation with Ein-horns apparatus, because in thelatter no allowance is made for tem-perature, pressure, etc., as shouldbe done in all volumetric gas anal-yses. Lohnsteins instrument con-sists of a U-shaped tube with a longarm, and another ending in a is poured into this bulb upto the zero mark on the scale of thelong arm. A definite quantity ofurine is poured over the mercury, alittle yeast is added, and the appa-ratus is closed with a glass stoppergreased in vaselin. The stopper isweighted with lead so as to preventthe escape of any gas. The appa-ratus is set aside at a fixed tem-perature (20° or 350 C), and themercury rises as the gas of fermen-tation develops. Its level is read directly on the scale ofthe tube in percentage of glucose. The temperature andtension in this method remain always the same. The disadvantages of all the fermentation methods aretheir inaccuracy and the fact that they require twenty- 1 Riforma Medica, March 30, 1904, p. Fig. 12.—Lohnsteins sac-charometer. QUANTITATIVE DETERMINATION OF SUGAR I17 four hours for their completion. According to Ogden, thefermentation tests yield results that are about percent, lower than those obtained with Fehlings method. Roberts1 comparative density method is also approximate,but is preferred by some, as it requires no apparatus tospeak of. Four ounces of the urine are placed in a 12-ounce bottle and a piece of compressed yeast is bottle is then stoppered with a nicked cork, to allowthe escape of C02, and set aside in a warm place. A tightlycorked 4-ounce bottle filled with the same urine withoutany yeast is placed next to it. Fermentation goes on foreighteen to twenty-four hours. The fermented urineis then decanted into a cylinder and its specific gravity istaken. At the same time the specific gravity of the un-fermented urine is also taken and the loss of density isnoted. According t
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