CURRENT TOPICS. 631 uncertain that the last three acids actually are present as glycerides. The presence of these acids (formic, acetic, and caproic) gives rise to the extremely high Reichert-Meissl number, as well as the unusual values of several other constants.
J. S. H. Micro Determination of Nitrogen.--L. N. LAPIN AND W. E. KILL (Zeit. klin. Medizin, I93I, xcviii, 278-285)convert the nitrogenous compounds (for instance, those present in a protein-free blood filtrate) into ammonium sulphate by a modified Kjeldahl digestion. The resulting mass is dissolved in 2o cc. of distilled water, and mixed with IO cc. of a modified Nessler solution and 2 cc. of Fehling solution. The resulting green solution is transferred to a porcelain dish. In a similar dish, a blank is prepared, containing the same volumes of Kjeldahl digestion reagent, and Nessler and Fehling solutions, and having the same total volume as the determination proper. A solution of ammonium chloride, containing o.I milligram of ammoniacal nitrogen per cc., is added to the blank from a micro burette until the blue color changes to the same shade of green as occurs in the determination proper. The blank then contains the same mass of nitrogen as is present in the sample used in the determination proper. J. S. H. Chlorocruorin.--This pigment, which is red in concentrated solution and green in dilute solution, occurs dissolved in the blood plasma of certain polychaete worms, and resembles hemoglobin in properties and in chemical composition. H. MUNRO FOX (Proc. Royal Soc., B, 1932, cxi, 356-363) has studied chlorocruorin, obtained from the worm Sp~rographis spallanzanii, by means of a spectrophotometer. He concludes that, at the temperature at which this worm lives, the chlorocruorin has an affinity for oxygen of the same order of magnitude as the affinity of hemoglobin for oxygen in the human body.
J. S. n.
Volatility of Tincture of Iodine.--Tincture of iodine may lose volatile constituents as a result of loosening of the stopper. This may be brought about by storage in a warm place and the resulting increase in pressure exerted by the contents of the bottle upon the stopper, or by prolonged action of the iodine upon the cork stopper and the resulting contraction of the cork. J. G. ROBERTS (Am.