窒素定量に於ける二三の接触剤に就て

概要

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The present paper deals with the experiment concerning the speed of digestion and the existence of loss of nitrogen by long digestion in Kjeldahl method, on oil cakes and carbonized manure, with 13cc sulfuric acid and 4.5 grams potassium sulfate for 1 gram sample, using yellow mercuric oxide, copper sulfate or selenium as the catalyst. The results obtained are as follows : - The appropriate amount of mercuric oxide is 0.2 gram, copper sulfate 0.5 gram and selenium 0.05 gram as the catalyst for each 1 gram sample. The digestion with mercuric oxide is complete in 45-60 minutes, with copper sulfate in 120-140 minutes and with selenium in 80-100 minutes, while permitting 1/100 error as to the standard, the digestion with copper sulfate and that with selenium is complete in about 60 minutes. According to the above results, as A. L. PRINCE and others reported, selenium has no advantage over mercuric oxide in saving time in the digestion for determination of nitrogen in fertilizers. Using selenium much less than 0.05 gram, the period of digestion becomes longer than that above mentioned, and if selenium is used more than this amount, the results is liable to become lower than that of the standard. Using the appropriate amount of these catalysts, and preventing the diminution of sulfuric acid and the bumping on long heating, it is observed that there is no danger of loss of nitrogen by this operation.
社団法人日本土壌肥料学会の論文
1937-10-15