BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. 507 BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. Digestive Activity and Composition of Different Fractions of the Pancreas.-I. J. H. Long, M. Hull, and H. V. Atkinson. (J. Amer. Chem. SOC., 1915, 37, 2427-2430.)-Preparations of minced pancreatic tissue were treated in a large laboratory centrifuge, having eight tubes of about 75 C.C. capacity each, and rotating up to 3,500 revolutions per minute.Generally only four of the tubes were charged with the finely minced mass, and rotated for forty-five minutes at a rate of 3,000 revolutions per minute. The mas9 gradually separated into three layers : at the bottom a mass of protein substance more compact than the original material; above this a distinct liquid layer nearly d e a r ; at the top a layer con- sisting largely of fat, with some protein and water.The proportions varied according to conditions; generally the lower layer amounted to 50 per cent. or more; in some cases the liquid and top layers were about 25 per cent. each. The three fractions have been examined separately in the case of pancreatic tissues from the hog, ox, and sheep, and the localisation of phosphorus, nitrogen, amylase, and trypsin, has been studied.The percentage of phosphorus in the fat was in all cases low, and the analyses seemed to indicate a, uniform composition of the fat in all the layers ; it would appear that the lipoid fraction cannot be more than 7 or 8 per cent. of the fat in any case. The amylase was located chiefly in the liquid fraction; it was only present in any considerable amount in the pancreas of the hog.The tryptic power was in all cases low, but the greatest activity was always found in the bottom layer, and the lowest activity in the liquid fraction. The liquid portions showed a slight acid reaction, substantially the same in all cases. J. F. B. Nephelometric Estimation of Purine Bases, including Uric Acid, in Urine and Blood.S. S. Graves and P. A. Kober. ( J . Amer. Chem. SOC., 1915, 37, 2430-2447.)-Salkomski’s reagent for purine bases has been modified to meet nephelometric conditions, and will precipitate santhine, hypoxanthine, guanine, adenine, and uric acid quantitatively in solutions containing as little as 0.0002 per cent. concentration. The reagent, as modified, consists of : 50 C.C.of ammoniacal silver508 ABSTRACTS OF CHEMICAL PAPERS nitrate solution (26.0 grms. AgNO, per litre, with sufficient ammonium hydroxide- e.g., 26-27 C.C. of sp. gr. 0.90, to prevent the separation of silver oxide); 8 C.C. of ammonium chloride solution (16.5 grms. NH,CI. per 100 c.c.) ; sufficient ammonia (usually about 9 c.c.) to redissolve any silver chloride formed ; an excess of ammonium hydroxide equal to 5 C.C.of sp. gr. 0.90 ; and lastly, water to make up 100 C.C. This reagent, after filtration, will keep indefinitely in stoppered bottles. In order to preserve the precipitates in perfect- suspension and prevent agglutination before t h s nephelometric readings can be taken, the use of a protective colloid has been adopted ; egg albumin is employed for this purpose, and certain optimum conditions for its use are prescribed.The reagent precipitates uric acid, together with the purine bases, and the uric acid may be eliminated, before precipitation, by oxidation with manganese dioxide prepared from potassium permanganate by the action of alcohol. Acting in a slightly alkaline medium the separation of the uric acid by this means is perfect, and takes place in three to four minutes, without any actiorP on the purine bases.The solution containing the mixture of uric acid and bases is neutralised, and 10 c.c., containing about 0*001 grm. of the substance, are treated with 0-1 C.C. of 6 per cent. ammonium hydroxide (1 part of 0.90 ammonia to 3 of water) ; 1 C.C. of a suspension of manganese dioxide is then added.This is made from 25 grms. of potassium permanganate in 500 c.c., washed on a filter, and sus- pended in 500 C.C. of water. After shaking for three to four minutes, the solution of purine bases free from uric acid is filtered; if necessary, 1 C.C. of a 4 per cent. solution of sodium acetate may be added to flocculate the manganese. The estima- tion of the uric acid is made by difference between reedings obtained with t h e original solution and one oxidised as described above.I n the analysis of urine it is necessary to make a preliminary separation of the uric acid and purine bases from the large proportion of inorganic salts present. This is effected by Salkowski’s reagent : 5 C.C. of urine and 5 C.C. of the modified reagent are mixed in a graduated tuhe and centrifuged for one to three minutes.The supernatant liquid is poured off, 10 C.C. of hydrochloric acid (1 : 100) are added to the residue, and the tube placed in boiling-water for two to five minutes. The contents are cooled and the volume made up to 15 C.C. The solution is centrifuged and the clear liquid drawn off for analysis. Uric acid is used as a standard cloud for both determinations.I n the estimation of the purine bases by oxidation of the uric acid, the residual traces of silver must be removed. This is effected by employing a solution of lithium car- bonate saturated with sulphuretted hydrogen to make the medium alkaline before oxidation. The silver sulphide is filtered off with the manganese, and it is noted that the manganese also removes the whole of the excess of alkali sulphide.In thO examination of blood, 5 volumes of a 3 per cent. solution of sulphosalicylic acid is an excellent reagent for removing all coagulable protein ; 5 volumes of Greenwald’s reagent (5 per cent.) is equally efficient, and has the advantage of not giving a yellow colour with ammonia. J. F. B. Use of P-Napthalenesulphonic Chloride for the Recognition of Partial Hydrolysis of Flesh Protein.w. Lob. (Clzem. Zeit., 1915, 39, 369-37O0)-This reagent, introduced by Bergell (cf. Zeitsch. physiol. Chem., 1914, 89, 465), is veryORGANIC ANALYSIS 509 useful for detecting the degree of hydrolysis which has taken place in flesh and in meat extracts, and may be used to ascertain the freshness of meat, etc. An extract prepared from the fresh autolysed flesh or meat extract is treated with sodium chloride and acetic acid, the mixture heated, filtered, and the reagent ie added to the filtrate. The precipitate is then collected, dissolved in sodium hydroxide solution, and the nitrogen estimated in an aliquot portion of the solution by Kjeldtlhl’s method. About 0.04 grm. of nitrogen is obtained from 250 grms. of fresh flesh, and the quantity of nitrogen thus obtained increases as the flesh hydrolyses with age. W. P. S.