Abstract
ABSENCE OF NITRATES.-Any of the recognized modifications of the Kjeldahl method may be used. The amounts of catalyst and acid required vary with the amount of organic matter to be oxidized. For 50-cc. aliquots of the alcoholic extract of fruit spurs, containing 1-3 mg. N, 15 cc. concentrated H2SO4 and 5-7 gm. of a mixture of 10 gm. K2SO and 1 gm. CuSO4 * 5H20 were adequate. Frothing is likely to be severe as the last of the water or alcohol is driven off. By careful regulation of the flames and occasional shaking it has been possible to make 30 digestions at once without loss. For the final titration the mixed methyl red-methylene blue indicator proposed by JOHNSON and GREEN (8) is excellent.
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Claims 0
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