Seyler, who found that by treating hematin with concentrated sulphuric acid and heating, there resulted a compound whose acid and alkaline solutions showed unusual spectral bands. To this new compound he gave the name "hematoporphyrin." Since its discovery, it has been recognized by a number of observers and under a variety of cir cumstances. Hematoporphyrin is identical with iron-free hematin (Nencki). A urine containing this coloring-matter, when viewed by reflected light, is opaque and almost black; or, in a thin layer, it is reddish-brown. In an isolated form Fig. 20.-Hematoporphyrin spectra: 1, Acid; 2, alkaline; 3, neutral. hematoporphyrin is nearly insoluble in water, in dilute acetic acid, benzol, and nitrobenzol; it is slightly soluble in ether, chloroform, and amyl alcohol, and readily soluble in alcohol, alkaline hydrates, and carbonates, as well as in dilute mineral acids. Spectra. The acid alcoholic solution shows (Fig. 20, 1) two absorption bands: one rather dark, situated between Frauenhofer's lines C and D, with its right border overlapping D; and the second, sharply defined, nearly intermediate between D and E. The alkaline solution presents (Fig. 20, 2) a four-banded spectrum as follows: A faint and very narrow band about midway between C and D; two between D and E, one with its left border near D, the other including E; the fourth band, which is the darkest of all, but which, however, is not well defined, includes nearly all of the space between 6 and F, and incloses F. The neutral and metallic spectra are represented in the accompanying illustration (Fig. 20, 3); they are less characteristic than the acid and alkaline spectra, and therefore will not be described here in detail. Clinical Significance. Since urine normally contains traces of hematoporphyrin, its presence becomes of importance only when it is present in large amounts. It was first discovered in the urine by Baumstark (1874) in a case of leprosy, and then by MacMunn, le Nobel, and others in acute articular rheumatism. Neusser found this pigment in cases of phthisis pulmonalis, and pleurisy with effusion. Perhaps its most frequent appearance in large amounts is following the prolonged use of sulphonal, trional, or tetronal; it is only rarely found after one or two doses of any one of these three drugs. It is commonly found in cases of lead-poisoning, of which Nakarai has reported six; the author has met with it in cases of lead-poisoning, but never in large quantities. This coloring-matter has also been observed in cases of intestinal tuberculosis (Nakarai). The bearing of nervous phenomena upon the production of hematoporphyrinuria is a subject that requires further study. In two cases reported by Rankin and Partington and one by the author, obscure nervous symptoms were prominent, and possibly had some bearing on the cause of the hematoporphyrinuria. Salkowski's Method for the Separation of Hematoporphyrin. "Take about 30 c.c. of urine, add baryta mixture (equal parts of a 10 per cent. solution of barium chloride and a saturated solution of barium hydrate), until it is completely precipitated. Wash once with water, and once with absolute alcohol, using the latter drop by drop. Transfer the precipitate to an evaporating dish, add from 6 to 8 drops of concentrated hydrochloric acid and sufficient absolute alcohol to make a thin pap, then stir thoroughly. Heat over a water-bath, filter through 1 Ogden, "Boston Medical and Surgical Journal," Feb. 24, 1898. a dry filter-paper, and finally add sufficient absolute alcohol to make from 8 to 10 c.c. of filtrate." This solution (acid) may be examined directly with the spectroscope for the bands of acid hematoporphyrin, or it may be rendered alkaline, preferably with ammonic hydrate, and examined for the characteristic bands of alkaline hematoporphyrin. The spectroscopic examination of this alcoholic solution must be made within a few hours after its preparation, since the solution readily decomposes, after which it is useless for observation. Detection. This coloring-matter can only be detected with certainty by means of the spectroscope. The four spectral bands of the alkaline solution are most characteristic. MELANIN. Melanin is a pigment that is sometimes found in the urine of persons suffering from pigmented tumors. It is usually found in solution in the urine, and more rarely in the form of small black granules which are in suspension. Freshly voided urine containing melanin is usually transparent and of a normal color. When, however, the urine is allowed to stand exposed to the air, the color changes to a brown, and finally to a black. Only in rare instances is the urine black when it leaves the body. Melanin is eliminated in the form of a chromogen,-melanogen,-which becomes oxidized in the air or by oxidizing agents, with a resulting dark or black color due to a deposit of the pigment, melanin. Just where this pigment is converted into a chromogen in the body has not yet been determined. Ganghofner and Pribram claim that the change takes place in the liver, but this is still a matter of doubt. Melanin is insoluble in water, ether, amyl alcohol, and dilute acids. It is readily soluble in sodic and ammonic hydrates, sodic carbonate, and monosodic phosphate; hence it is not precipitated carbon. It contains iron, sulphur, and nitrogen. The chromogen, melanogen, is readily oxidized by potassium bichromate with sulphuric acid, a five per cent. solution of chromic acid, fuming nitric acid, potassium permanganate, and potassium chlorate with hydrochloric acid, with a resulting black color. Litten observed that urine containing melanin did not undergo ammoniacal fermentation, but, instead, became more acid than normally with the formation of a thick fungus-growth on its surface. He also found that the urine often contained a reducing substance similar to glucose; such a reaction, however, has not been reported by other observers. Clinical Significance.-Melanuria is most commonly seen in case of melanotic sarcoma in some part of the body, not necessarily in the kidneys. It has, very rarely, been observed to a marked degree in severe wasting diseases, and has also been observed in persons suffering from repeated attacks of intermittent fever. The urine of individuals suffering from melanotic new growths may be entirely free from melanin while the growth is actively progressing. Detection.-I. The most sensitive test for the presence of melanin is the addition of bromine water, which causes a yellow precipitate that gradually blackens (Zeller). 2. A few drops of a fairly concentrated solution of ferric chloride will cause the urine to turn gray: if more be added, a precipitate of phosphates falls, carrying the coloring-matter with it, and again dissolves with an excess of the iron solution (v. Jaksch, Pollak). 3. Sodium nitroprusside with caustic potash and acetic acid gives a deep-blue color, probably due to the formation of soluble and insoluble Prussian blue (v. Jaksch). This test, however, can not always be obtained with melanin that has been isolated from the urine, and the reaction must not be regarded as a test for melanin, or only when other tests have shown the presence of melanin or melanogen. Mörner separated the coloring-matter that was in the form of a chromogen in the urine by precipitating with baryta water, and then purifying. PTOMAINES AND LEUCOMAINES.-TOXICITY OF URINE. Ptomaines may be defined as organic chemic compounds, basic in character, and formed by the action of bacteria on nitrogenous matter. On account of their basic properties, in which they resemble the vegetable alkaloids, ptomaines may be called putrefactive alkaloids. They have also been called animal alkaloids, but this is a misnomer, because, in the first place, some of them are formed in the putrefaction of vegetable matter, and, in the second place, the term "animal alkaloids" is more properly restricted to the leucomaines,-those basic substances which result from tissue metabolism in the body. While some of the ptomaines are highly poisonous, this is not an essential property, and others are wholly inert. Indeed, the greater number of those which have been isolated up to the present time do not, when employed in single doses, produce any apparent harmful effects. Brieger restricts the term ptomaine to the nonpoisonous basic products, and designates the poisonous ones as "toxines." Since all putrefaction is due to the action of bacteria, it follows that all ptomaines result from the growth of these organisms. The kind of ptomaine formed will, therefore, depend upon the individual bacterium engaged in its production, the nature of the material being acted upon, and the conditions under which the putrefaction goes on, such as the temperature, the amount of oxygen present, and the duration of the process. All ptomaines contain nitrogen as an essential part of their basic character. In this they resemble the vegetable alkaloids. Some of them contain oxygen, while others do not. The latter correspond to the volatile vegetable alkaloids, nicotine and coniine, and the former correspond to the fixed alkaloids. It was formerly supposed that putrefaction was simply oxidation, but the researches of Pasteur and others have demonstrated the fact that countless myriads of minute organisms are engaged constantly in transforming matter from organic to the inorganic form. Hermetically seal the organic matter and it will remain unchanged indefinitely. According to Pouchet, healthy urine contains traces of certain toxic substances of an alkaloidal nature; and according to the researches of Bouchard, Lépine, and Guerin, these bodies are more abundant under diseased conditions. They were found by A. Villiers as an invariable manifestation in measles, diphtheria, and pneumonia. Pouchet found in the urine of cholera an alkaloid which was not identical with that observed by him in the feces of the same discase. Feltz found similar bodies in the urine of cancer patients, and Lépine in that of pneumonia. Toxines have been found in the urine of scarlet fever and pneumonia (Albu); in |