Abstract

                                When an organic substance containing nitrogen-such as a protein -is continuously boiled with concentrated sulphuric acid, it undergoes digestion, yielding carbon dioxide and sulphur dioxide (together with considerable amounts of acid fume) as gaseous products and leaving a residue, which generally contains all the nitrogen as ammonium sulphate. On this reaction is based the well-known Kjeldahl method, ¹ which was first introduced in 1883 and which, in one or the other of its several modifications is still most extensively adopted for the esti- mation of nitrogen. A conservative estimate, would indeed show that in scientific research alone-apart from routine analyses in Govern- ment laboratories, factories or private practice-a few millions of determinations are being annually carried out by that method.

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