474 THE ANALYST, BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. New Method for the Estimation of Lactic Acid in Animal Organs and Fluids. E. Jerusalem. (Biochem. Zeits., 1908, 12, 361-389.)-1n the method pro- posed, the lactic acid is extracted from the substance under examination by means of ether and then oxidised by permanganate ; the aldehyde formed is estimated by the iodometric (iodoform) method, and the quantity found is equivalent to the lactic acid present. As lactic acid is by no means readily extracted from its aqueous solution by ether, the solution should be evaporated almost to dryness, and the pasty mass then extracted. A special extraction apparatus is described for this purpose, the residue being placed in an extraction thimble contained in a wide glass tube; the ether vapours are condensed at the top of the tube, and the drops of ether, falling on to the residue in the thimble, pass through the latter and down a long vertical tube attached to the bottom of the wide tube.The lower part of this vertical tube is bent upwards in a spiral form, so that any drops of water are well extracted by the ether before the latter finally passes again into the extraction flask. The ethereal solution of the lactic acid, obtained after several hours’ extraction, is evaporated, and the residue is introduced into a flask attached to a condenser. About 150 C.C. of water and 10 C.C. of concentrated sulphuric acid are added, the solution is boiled, and potassium permanganate solution is added drop by drop by means of a tapped funnel. A current of air is drawn through the apparatus during the whole operation, and the coloration produced by each drop must disappear before the next drop is admitted.In this way the aldehyde produced is removed as soon as formed, and is not further acted on by the succeeding quantities of permanganate added. IVhen the coloration obtained on adding a drop of permanganate no longer disappears, the addition of permanganate is stopped and the current of air is continued for some time. The lower end of the condenser is connected with absorption vessels con- taining water, in which the aldehyde is collected. At the end of the operation, theTHE ANALYST. 475 contents of the receivers are mixed, rendered alkaline with sodium hydroxide, and treated with a known excesB of i: iodine solution. At the end of five minutes the mixture is acidified with hydrochloric acid, and the excess of iodine is titrated with thiosulphate solution.The quantity of lactic acid is then calculated from the amount of iodine used. Of the substances which may interfere with the accuracy of the estimation, P-hydroxybutyric acid has the most influence; but, as it is much less readily attacked by permanganate, the point at which the lactic acid is corn- pletely converted into aldehyde before the hydroxybutyric acid is acted on can usually be noted; the latter acid decolorises the permanganate extremely slowly, whilst lactic acid does so quickly. Cholesterol, succinic acid, hippuric acid, lecithin, skatol, benzene, fatty acids, bile acids, and the colouring matter of urine and bile, do not interfere with the estimation.For the estimation of lactic acid in urine, the latter is freed from albumin, rendered ainmoniacal and evaporated to a, syrup ; this is treated with hydrochloric acid, extracted with ether, and the residue obtained on evaporating the ether is heated with dilute ammonia until every trace of ether has been expelled. In the case of blood and milk, the albuminoids are removed by treatment with potassium hydrogen phosphate and phosphotungstic acid ; the filtrate is then evaporated with The estimation is then carried out as described above. ammonia, and the process carried out as prescribed for urine. w. P. s. The Action of Acids and Rennet on Human Milk. Engel. (I3iocltcnz. Zeztsch., 1908, 13, 89-lll.)-The experiments recorded show that human milk is coagulated by hydrochloric, lactic, oxalic, and sulphuric acids when the quanbity of the acid present amounts to from 2 to 3 C.C.of T6 solution per 10 C.C. of milk, and between these limits total coagulation is sharply defined. In the case of phosphoric and acetic acids from 5 to 12 C.C. of the 2G acid are required to coagulate 10 C.C. of the milk. The coagulation by rennet bears a certain relation to the amount of acid present, but the action of the enzyme is less limited than is that of the acids. Acids produce a cosgulum consisting of casein, whilst rennet precipitates a calcium com- pound of casein. w. P. s. A Reaction distinguishing Phosphoprotein from Nucleoprotein and the Distribution of Phosphoproteins in Tissues.R. H. A. Plimmer and F. B. Scott. (Trans. Chenz. SOC., 1908, 93, 1699-1721.)--The test depends on the fact that the whole of the phosphorus (except for a negligible quantity) is eliminated as phosphoric acid from a phosphoprotein by treating the latter with 1 per cent. sodium hydroxide solution for twenty-four hours at a temperature of 37' C., whilst other organic phosphorus compounds, such as nucleoproteins, lecithin, glycerophosphoric acid, and nucleic acid, do not yield inorganic phosphoric acid when so treated. The method consists in coagulating the tissue with alcohol, thoroughly extracting the lecithin with alcohol and ether, and then treating the coagulated protein with 1 per cent. sodium hydroxide solution, after the phos- phates have been removed by repeated extraction with very dilute hydrochloric acid.I t is shown that phosphoproteins are present in milk, egg-yolk, and in the476 THE ANALYST, ova of fishes ; that is, thuy &re mainly distributed in the substances which constitute the food-stuffs of the embryo bird and fish and the young mammal. A small quantity of phosphoprotein is also present in the pancreas. w. P. s. Reliability of Methods used for Estimating Sugar in Urine. C. Funk. (Zeitscli. yhysiol. Clzem., 1908, 56, 507-511.)-Differences which have been observed between the results obtained by the polarimetric method and Bang’s method (ANALYST, 1907, 32, 180) for the estimation of sugar in diabetic urine are not d m to the presence of an unknown sugar, but to the fact that the urine contains P-hydroxybutyric acid.The latter is without influence on the results obtained by Bertrand’s volumetric process, in which the cuprous oxide precipitated by the sugar from Fchling’s solution is dissolved in ferric sulphate solution, and tho ferrous sulphate produced is titrated with permanganate. The author considers that, whilst Bang’s method is trustworthy for the estimation of pure sugars, it is useless for the examination of diabetic urine. w. P. s. A Colour Reaction of‘ Diabetic Urine. 0. Gaupp. (Biochenb. Zeitsch., 1908, 13, 138-141.)-A reaction described by Strzyzowski (Therap. Monatsclz., 1905) as being indicative of severe diabetes, is based on the formation of a green fluorescent coloration when the urine of the patient is treated with a 5 per cent. formaldehyde solution and allowed to stand for forty-eight hours. The author finds, however, that this reaction is not chwacteristic of diabetes, but is given by the urine in most cases of cachexia. The coloration is due to an inzrease in the amount of ammonia in the urine, and to the simultaneous presence of aceto-acetic acid, and may be produced artificially by mixing ammonia, aceto-acetic acid, and formaldehyde. w. P. s.