urine to dryness, fuse the residue with potassium nitrate (KNO,), which oxidizes all the sulphur to sulphate, take up with water and hydrochloric acid, add barium chloride, and the precipitate (BaSO) represents the total sulphur present. Deduct the amount belonging to sulphuric acid, previously determined, and the remainder represents the neutral sulphur. METABOLISM OF SULPHUR.-The total amount of sulphur in the urine runs proportionally parallel with the amount of nitrogen; that is to say, the amount is proportional to the amount of proteid destroyed. The amount of ethereal sulphate is dependent upon the putrefactive production of indol, skatol, phenol, and cresol in the intestinal canal, which on absorption form a synthetical combination with the traces of sulphate in the blood. Concerning neutral sulphur it is known that taurin is one source of it. If taurin be fed directly, the amount of neutral sulphur in the urine increases (Salkowski), and in a dog with a biliary fistula the neutral sulphur decreases but does not entirely disappear. In a well-fed dog with a biliary fistula Voit found the quantity of sulphur in the bile to be about 10 to 13 per cent. of that in the urine. This biliary sulphur (taurin) is normally reabsorbed, as the quantity of sulphur in the feces (FeS, Na,S) is small and derived principally from proteid putrefaction. The amount of neutral sulphur in the urine is greatest under a meat diet, least when fat or gelatin is fed; the sulphur of gelatin is very small in quantity. In dyspnoea the amount of neutral sulphur increases in the urine, on account of insufficient oxidation. The neutral sulphur of the urine includes potassium sulphocyanide (originally derived from the saliva), likewise a substance which on treatment with calcium hydrate yields ethyl sulphide, (CH),S,' and there are present other unknown compounds (see p. 547). When an animal eats proteid and neither gains nor loses the same in his body, the amount of sulphur ingested is equal to the sum of that found in the urine and feces. If sulphur be eaten, it partially appears as sulphate in the urine. Sulphates eaten pass out through the urine. They play no part in the life of the cell. CHLORINE, Cl = 35.5. Free chlorine is not found in the organism, and when breathed it vigorously attacks the respiratory mucous membranes. Chlorine is found combined in the body as sodium, potassium, and calcium chlorides, as hydrochloric acid, and it is said to belong to the constitution of pepsin." Hydrochloric Acid, HCl, is found to a small extent in the gastric juice. Preparation.-(1) If sunlight acts on a mixture of equal volumes of chlorine and hydrogen, they unite with a loud explosion. 1 Kunkel: Archiv für die gesammte Physiologie, 1877, Bd. 14, S. 353. Zeitschrift für Biologie, 1894, Bd. 30, S. 554. 3 Harnack and Kleine: Zeitschrift für Biologie, 1899, Bd. 37, S. 417. ✦ J. J. Abel: Zeitschrift für physiologische Chemie, 1894, Bd. 20, S. 253. E. O. Schoumow-Simanowski: Archiv für exper. Pathologie und Pharmakologie, 1894, Bd. 33, S. 336. (2) By the action of strong sulphuric acid on common salt, 2NaCl + H2SO, = Na2SO4 + 2HCl. (3) By the action of primary acid phosphate of sodium on common salt, NaCl + NaH2PO1 = Na2HPO4 + HCl. 4 This, according to Maly, represents the process in the cells of the gastric glands. Properties.-Hydrochloric acid readily unites with most metals, forming chlorides. It causes a gelatinization of the proteids and seems to unite with them chemically. Such gelatinization is a necessary forerunner of peptic digestion. The cleavage products of peptic digestion (peptones, proteoses, etc.) combine with more hydrochloric acid than the original more complex proteid.' Free hydrochloric acid of the strength of the gastric juice (0.2 per cent.) inverts cane-sugar at the temperature of the body, and inhibits the action of bacteria. Hydrochloric acid is derived from decomposition of chlorides in the secreting cells of the stomach. It has been shown that the excretion of common salt in the urine is decreased during those hours that the stomach is active, while the acidity of the urine decreases. If, in a dog with a gastric fistula, the mucous membrane of the stomach be stimulated and the gastric juice be removed as soon as formed, the urine becomes strongly alkaline with sodium carbonate (the excess of Na liberated taking this form) while the chlorides may entirely disappear from the urine. Respiration in an atmosphere containing 0.5 per cent. HCl gas becomes very uncomfortable after twelve minutes.* If the bases (K, Na, Ca, Mg, Fe) of gastric juice and then the acid radicals (Cl and PO) be determined, and the phosphoric anhydride be united with the proper bases, and then chlorine with the rest of the bases, there still remains an excess of chlorine which can only have belonged to the hydrochloric acid present. To detect free hydrochloric acid put three or four drops of a saturated alcoholic solution of tropæolin 00 in a small white porcelain cover, add to this an equal quantity of gastric juice, evaporate slowly, and the presence of hydrochloric acid is shown by a beautiful violet color, not given by any organic acid." Günzburg's reagent consisting of phloroglucin and vanillin in alcoholic solution, warmed (as above) with gastric juice containing free hydrochloric acid, gives a carmine-red mirror on the porcelain, not given by an organic acid.“ CHLORINE IN THE BODY is ingested as chloride, and leaves the body as such, principally in the urine, likewise through the sweat and tears, and in traces in the feces. BROMINE, Br= 80. Salts of bromine are found in marine plants and animals, but their physiological importance has not been established. Bromine is a fluid of intensely disagreeable odor, 1 Chittenden: Cartwright Lectures on Digestive Proteolysis, 1895, p. 52. 2 Ferris and Lusk: American Journal of Physiology, 1898, vol. i. p. 277. E. O. Schoumow-Simanowski: Archiv für exper. Pathologie und Pharmakologie, 1894, Bd. 33, S. 336. Lehmann: Archiv für Hygiene, Bd. 5, S. 1. 5 Boas: Deutsche medicinische Wochenschrift, 1887, No. 39. Günzburg: Centralblatt für klinische Medicin, 1887, No. 40. whose vapors strongly attack the skin, turning it brown, and likewise the mucous membranes of the respiratory passages. Hydrobromic Acid, HBr, may be prepared by the action of water on phosphorus tribromide, PBr2+ 3H2O = 3HBr + H3PO3. It is a colorless gas of penetrating odor. If sodium bromide be given to a dog in the place of sodium chloride, fifty per cent. and more of the hydrochloric acid may be supplanted by hydrobromic acid in the gastric juice.' The various organs are then found to contain bromine, especially the kidneys through which it may be eliminated. IODINE, I=127. Like bromine, the salts of iodine are found in many marine plants and animals, especially in the algae. It is found in the thyroid gland. Iodine is prepared in metallic-looking plates, almost insoluble in water, but soluble in alcohol (tincture of iodine). Iodine is still more strongly corrosive in its action on animal tissue than is chlorine or bromine, and is an antiseptic and disinfectant. A slight trace of free iodine turns starch blue. Hydriodic Acid, HI, is prepared like hydrobromic acid, by the action of water on tri-iodide of phosphorus. An aqueous solution of hydriodic acid introduced into the stomach is absorbed, and shortly afterward iodine, as alkaline iodide, may be detected in the urine. On administration of sodium iodide to a dog with his food, only very little hydriodic acid appears in the gastric juice." 5 CIRCULATION IN THE BODY.-Iodine or iodides given are rapidly eliminated in the urine, in smaller amounts in saliva, gastric juice, sweat, milk, etc. It is noticed that for weeks after the administration of the last dose of potassium iodide, traces of iodine are found in the saliva, and none in the urine. The explanation lies in the presumption that iodine has been united with proteid to a certain extent, and appears in such secretions as saliva, which contains materials derived from proteid through glandular manufacture.* A similar explanation avails in the case of Drechsel's discovery that, in patients who have been treated with iodides, iodine may be detected in the hair (the keratin of hair being derived from other proteid bodies.) Whether free iodine or hydriodic acid is liberated in the tissues from ingested iodides are disputed points. Baumann discovered an organic compound of iodine occurring in the thyroid gland and containing as much as 9.3 per cent. of iodine. Roos' states that this thyroiodine from sheep's thyroid constantly contains about 5 per cent. of iodine. When fed it increases the metabolism of proteid and fat and acts as an antitoxine. According to Blum, the iodine is combined with the proteids of the thyroid in varying quantity, and any liberated iodine may act within the thyroid to destroy toxic bodies, especially nerve toxines. Oswald," on the contrary, states that the effective principle of the thyroid is a thyroglobulin containing 1.66 per cent. of iodine. This thyroglobulin treated with acids yields thyroiodine, which contains 14.4 per cent. of iodine. Thyroids which contain no iodine have no physiological effect upon metabolism." 8 10 Nencki and Schoumow-Simanowski: Archiv für exper. Pathologie und Pharmakologie, 1895, Bd. 34, S. 320. 2 Rosenthal: Zeitschrift für physiologische Chemie, 1896, Bd. 22, S. 227. 3 Nencki and Schoumow-Simanowski: Loc. cit. Schmiedeberg: Grundriss der Arzeinmittellehre, 2d ed., 1888, S. 197. 5 Centralblatt für Physiologie, 1896, Bd. 9, S. 704. 6 Zeitschrift für physiologische Chemie, 1895, Bd. 21, S. 319. 11 Zeitschrift für physiologische Chemie, 1899, Bd. 27, S. 14. Ibid., 1898, Bd. 25, S. 1. FLUORINE, F = 19. Fluorine is found in the bones and teeth, in muscle, brain, blood, and in all investigated tissues of the body, though in minute quantities. In one liter of milk 0.0003 gram of fluorine have been detected. Fluorine is found in plants, and in soil without fluorine plants do not flourish. It seems to be a necessary constituent of protoplasm. Free fluorine is a gas which cannot be preserved, as it unites with any vessel in which it is prepared. Hydrofluoric Acid, HF, is prepared by heating a fluoride with concentrated sulphuric acid, in a platinum or lead dish, CaF2+H2SO1 = CaSO, + 2HF. Properties.-Hydrofluoric acid is a colorless gas, so powerfully corrosive that breathing its fumes results fatally. Its aqueous solutions are stable, but can be kept only in vessels of platinum, gold, lead, or india-rubber. It etches glass, uniting to form volatile silicon fluoride, SiO2+ 4HF=SiF, + 2H2O. CIRCULATION IN THE BODY.-Tappeiner and Brandl2 have shown, on feeding sodium fluoride (NaF) to a dog in doses varying between 0.1 and 1 gram daily, that the fluorine fed was not all recoverable in the urine and feces, but was partially stored in the body. On subsequently killing the dog, fluorine was found in all the organs investigated, and was especially found in the dry skeletal ash to the extent of 5.19 per cent. reckoned as sodium fluoride. From the microscopic appearance of the crystals seen deposited in the bone, the presence of calcium fluoride was concluded. In this form it normally occurs in bones and teeth. NITROGEN, N=14. Free nitrogen constitutes 79 per cent. of the volume of atmospheric air. It is found dissolved in the fluids and tissues of the body to about the same extent as distilled water would dissolve it. It is swallowed with the food, may partially diffuse through the mucous membrane of the intestinal tract, but forms a considerable constituent of any final intestinal gas. It is found in the atmosphere combined as ammonium nitrate and nitrite, which are useful in furnishing the roots of the plant with material from which to build up proteid. Bacteria upon the roots of certain vegetables combine and assimilate the free nitrogen of the air (Hellriegel and Willforth). Cultures of alge do the same. Preparation.-(1) By abstraction of oxygen from air through burning phosphorus in a bell jar over water, pentoxide of phosphorus being formed, which dissolves in the water and almost pure nitrogen remains. (2) By heating nitrite of ammonium, NH,NO2 = 2N + 2H2O. Properties.-Nitrogen is especially distinguished by the absence of chemical affinity for other elements. It does not support combustion, and in it both a 1 G. Tammann: Zeitschrift für physiologische Chemie, 1888, Bd. 12, S. 322. 3 P. Kossowitch: Botanische Zeitung, 1894, Jahrg. 50, S. 97. flame and animal life are extinguished, owing to lack of oxygen. It acts as a diluent of atmospheric oxygen, thereby retarding combustion, but on higher animal life it is certainly without direct influence. Ammonia, NH,, is found in the atmosphere as nitrate and nitrite to the extent of one part in one million. It is found in the urine in small quantities, is a constant product of the putrefaction of animal matter, and is a product of trypsin proteolysis. Preparation. (1) Through the action of nascent hydrogen on nascent nitrogen. This may be brought about by dissolving zinc in nitric acid, 3Zn + 6HNO, = 3Zn(NO3)2 + 6H. 10H + 2HNO1 = 6H2O + 2N. Ammonia is produced in a similar way in the dry distillation of nitrogenous organic substances in absence of oxygen, being therefore a by-product in the manufacture of coal-gas. In putrefaction nascent hydrogen acts on nascent nitrogen, producing ammonia, which in the presence of oxygen becomes oxidized to nitrate and nitrite, or in the presence of carbonic oxide is converted into ammonium carbonate. Ammonium nitrite is likewise formed on burning a nitrogenous body in the air, in the evaporation of water, and on the discharge of electricity in moist air, 2N+ 2H2O = NH,NO2. At the same time a small amount of nitrate is formed in the above three processes, 2N + 2H2O + 0 = NH,NO. Hence these substances find their way into every water and soil, and furnish nitrogen to the plant. The value of decaying organic matter as a fertilizer is likewise obvious. Properties.-Ammonia is a colorless gas of pungent odor. It readily dissolves in water and in acids, entering into chemical combination, the radical NH, appearing to act like a metal with properties like the alkalies, and its salts will be described with them. Very small amounts of ammonia instantly kill a nerve, but upon muscular substance it acts first as a stimulant, provoking contractions: 1 part of ammonia in 500 of water will kill an amœba, and 1 part in 10,000 will slow and finally arrest ciliary motion.1 AMMONIA IN THE BODY.-If it be agreed with Hoppe-Seyler that normal decomposition in the tissues is analogous to putrefaction, then nascent hydrogen acting on nascent nitrogen in the cell produces ammonia, which in the presence of carbonic acid becomes ammonium carbonate, and in turn may be converted into urea by the liver. If acids (HCl) be fed to carnivora (dogs) the amount of ammonia present in the urine is increased, which indicates that an amount of ammonia usually converted into urea has been taken for the neutralization 1 Bokorny: Pflüger's Archir, 1895, Bd. 59, S. 557. |