largely its content of soluble calcium, as the following experimental data among others, clearly show. Three equal weights of a given specimen of feces were treated with equal volumes of distilled water. To one portion, 2 to 3 drops of acetic acid sol. were added; to another, 2 to 3 drops of ammonium hydroxid sol., and each mixture rendered homogeneous by thorough stirring. The extracts were then filtered and the quantities of calcium in the filtrates determined, with the following results: 200 c.c. of fecal extract with distilled water 200 c.c. of fecal extract with dilute acetic acid 200 c.c. of fecal extract with dilute ammonia Calcium, CaO 0.0314 gm. 0.2170 gm. 0.0225 gm. In order further to test my general conclusion, I made direct experiments, on men, by means of rectal injections of solutions of ammoniacal and calcareous salts of volatile fatty acids. These experiments have shown that the ammoniacal salts cause strong polyuria, whereas the calcareous induce marked hypouria. The ammoniacal injections were prepared with ammonia (3.825 gm. of NH ̧) neutralized with butyric acid in the presence of rosolic acid and made up to 100 cc. The calcareous injections were prepared with 5 cc. of pure acetic acid neutralized with carbonate of lime, filtered, washed, and made up to 100 cc. The daily quantity was diluted four or five times with water and fractionally injected, in each case. Below are recorded the results of an experiment on a given individual during four periods of several days each. Throughout the experiment the daily urine was collected and analyzed. Only the averages for each period are given below. (The daily data for this and similar experiments may be found in the book referred to above (13).) Calcium CaO, gm. 0.2426 SECOND PERIOD. Polyuric effect of injected butyrate of ammonia FIRST PERIOD. Normal conditions Daily averages Daily averages Daily averages Daily averages Volume, cc. 1290.6 2248.0 1384.0 0.2989 THIRD PERIOD. Hypouric effect of injected acetate of calcium ...... 0.4503 Volatile fatty acid (n/10 NaOH sol.), cc. FOURTH PERIOD. Polyuria provoked by ingested water; no injections 24.51 31.56 68.7 25.38 2 This average does not show the full hypouric effect of calcium acetate, though its action was very strong. This period followed the period of polyuria but, notwithstanding this fact, the volume of urine in the latter part of the period was below normal. These analytic results show that the proportions of calcium and volatile fatty acids are practically uniform in the urine of the same person, under normal conditions and during the polyuria produced by the drinking of an abundance of water. The rectal absorption of calcium salts of volatile fatty acids produces a simultaneous, rapid, and striking increase of both calcium and fatty acid in the urine. The small increase of volatile fatty acid in the urine above normal or above the polyuria potatoria, after rectal injection of ammonium butyrate, is not due to direct passage into the urine of the absorbed fatty acids in combination with ammonia. This small increase may be explained by a formation of calcium salts through the solvent action of the ammonium butyrate sol. on the carbonates and phosphates of calcium that occur abundantly in every feces, as a simple and direct experiment on feces shows (similar to the one mentioned before). An exact investigation of the nature of the volatile fatty acids in the urines of persons submitted to the action of rectal injections shows that butyric or acetic acid predominates in the urine when rectal injection of a salt of one or the other of these acids is used. Finally, by a suitable mixture of both kinds of salts (ammonium and calcium), it is possible to obtain simultaneously the polyuria, the calcariuria and the lipaciduria, as they occur in diabetes. The polyuria is induced by the salt that yields urea (17). General deductions. The foregoing data show that calcium, and with it volatile fatty acids, describe a very interesting "retrograde circulation" in the human body, the biological mechanism of which has not hitherto been demonstrated. The calcium and volatile fatty acids in urine are generally considered final products or residues of tissue metabolism. These investigations demonstrate that the presence of most of each substance in the urine may be explained by the "retrograde circulation of the calcium," which is initiated by intestinal putrefaction. Although in the present state of our knowledge of this subject, it is impossible to say that all the calcium and all the volatile fatty acids of the urine have the exclusive intestinal and bacterial origin above mentioned, nevertheless the data at hand warrant the conviction, already expressed, that most of each arises in the manner sug gested. It is also impossible to say, at present, whether the calcium that is normally absorbed from ingested food is excreted exclusively by the intestinal mucous membrane or whether a portion of it is also eliminated in the urine. Many reasons, and the results of numerous experiments which cannot be explained here, are entirely favorable to the first of these two possibilities. Calcariuria and lipaciduria, which are very commonly observed in diabetes and other maladies, may be explained by the "retrograde circulation of calcium." This view, if verified by experiment, would modify very profoundly our conception of the nature of these diseases, which are considered today, perhaps too exclusively, “nutritional" disturbances. The part which the calcium of "retrograde absorption" plays in the pathogeny of arteriosclerosis is a very important matter for consideration. Those who may be interested in this phase of the subject will find a description of an extensive study of it, in the book referred to above (13). [The author of this paper is now in the United States and may be addressed in care of the BIOCHEMICAL BULLETIN. Ed.] BIBLIOGRAPHY I. LOEPER and BÉCHAMP: Compt. rend. de la soc. de biol., 23 Juillet, 1910. 2. ALBU and NEUBERG: Physiologie und Pathologie des Mineralstoffwechsels, Berlin, 1906, p. 116. 3. V. NOORDEN and BELGRAD: Berl. klin. Wochenschr., 1894, No. 10. 4. BLAUBERG: Zeitschr. f. Biol., 1900, xxii, p. 36. 5. MÜLLER: Virchow's Archiv, 1893, cxxxi; Supplementheft, pp. 2, 52. 6. TIGERSTEDT: Skand. Archiv f. Physiol., 1904, xvi, p. 67. 7. RENVALL: Ibid., p. 94. 8. SALOMON and WALLACE: Medizin. Klinik, 1909, No. 16. 9. VOIT: Zeitschr. f. Biol., 1892, xxix, p. 325. 10. SALKOWSKI: Virchow's Archiv, 1871, liii, p. 209. II. URY: Deutsche med. Wochenschr., 1901, No. 41. 12. SOETBEER: Jahr. f. Kinderheilk., 1902, p. 1. 13. PALACIOS: Chimie pathologique tropicale de la région Atlantique, Brentano's, New York, 1914. (Referred to by Gies in a brief review: BIOCHEM. BULL., 1914, iii, p. 537.) 14. NEUBAUER-HUPPERT: Analyse des Harns, Wiesbaden; 1898, p. 746. 15. SCHMIDT and STRASBURGER: Die Fäzes des Menschen, p. 224. 16. STRAUSS and PHILIPPSOHN: Zeitschr. f. klin. Med., 1900, xl, p. 369. 17. PALACIOS: Extraphysiological or putrefactive urea; Amer. Jour. of Med. Sciences, 1915, cxlix, p. 267. A SIMPLE, EFFICIENT, AND ECONOMIC FILTER Its application to the filtration of the yellow precipitate in phosphoric-acid estimations1 S. L. JODIDI AND E. H. KELLOGG (Office of Plant Physiological and Fermentation Investigations, Bureau of Plant Industry, U. S. Department of Agriculture, Washington, D. C.) (Received for publication, July 21, 1915). INTRODUCTION. General considerations in connection with our work on the chestnut-blight disease led us to make phosphoric-acid determinations for the various barks, healthy and infected, in accordance with Neumann's2 method. It was soon found by the senior author3 that while Neumann's method is reliable and convenient, the calculation-factor, 0.554, is too low under certain conditions, a finding in full agreement with the work of Heubner.* Further investigation revealed the fact that the amount of water used for washing the yellow precipitate has a certain influence on the calculation-factor. While the work according to Neumann's method was going on, we were impressed by the fact that the filtration of the ammonium-phosphomolybdate precipitate through a folded filter, as recommended by Neumann, is a tedious and timeconsuming operation. A search for a better filtering medium finally led us to the paper-pulp filter. New mechanical devices, like new chemical methods, are of more or less importance to science, which is true, e. g., of the wellknown Gooch crucible (as well as of the Munroe crucible), the intro 1 Presented at the Second Pan-American Scientific Congress, Washington, D. C., January 4, 1915, and published by permission of the Secretary of Agriculture. 2 Neumann: Z. physiol. Chem. 37, 129 (1902-03); 43, 35 (1904-05). 3 Jodidi: Journ. Amer. Chem. Soc., 37, 1708 (1915). • Heubner: Biochem. Z., 64, 393 (1914). 6 Jodidi and Kellogg: Jour. Franklin Institute, 180, 349 (1915). • Munroe: Chem. News, 58, 101 (1888); Jour. Analyt. Chem., 2, 241 (1888). |