H^MATOPORPHYRIN. 625 



water. The solutions have a rich orange colour ; only when very dilute 

 and quite free from impurity do they exhibit a pink tint. All solutions 

 of the pigment are decolorised on exposure to light, even to subdued 

 daylight. On the other hand, light has little effect upon the solid 

 pigment, and none at all upon pink urate sediments. 



When solid uroerythrin is treated with solutions of the caustic 

 alkalies, a remarkable green coloration is produced (Thudichum). Green 

 derivatives from animal pigments are so uncommon that the reaction is 

 highly characteristic. It can be well seen when a little pink urate 

 deposit is collected upon a filter, dried, and then touched with a drop of 

 sodium-hydrate solution. If a solution of the pigment be treated with the 

 same reagent, a rapid play of colours may frequently be seen, from pink, 

 through purple and blue, to grass-green. With acids, colour-reactions 

 also occur, but they are somewhat less certain, being dependent upon 

 exact conditions of experiment. If to a solution of the pigment 

 sulphuric acid be added, the deep orange colour changes to a brilliant 

 carmine. Hydrochloric acid produces a rose-pink, phosphoric acid a 

 salmon-pink. 



Examined spectroscopically, a solution of uroerythrin, at a suitable 

 degree of dilution, shows two somewhat ill-defined absorption-bands 

 united by a shading of less intensity (Macmunn). The more red-ward of 

 these is seen in the green between the lines D and E, and nearer the 

 latter ; the other closely agrees in position with the ordinary urobilin 

 band at F (Fig. 57, Spectum 7). Pink urate sediments and the carmine 

 derivative produced by sulphuric acid agree in giving a single banded 

 spectrum, namely, a broad band extending from the D line towards violet. 



(d) Hsematoporphyrin. In 1881, Neusser 1 and Macmunn 2 observed 

 the occurrence in urine of pigments closely related to hsematoporphyrin. 

 During the following decade the work of le Nobel, Stockvis, Salkowski, 

 Hammarsten, Copeman, and others extended this discovery, and it 

 became established that hsematoporphyrin itself is a constituent of 

 certain pathological urines. In 1892, A. E. Garrod 3 showed that it 

 is also to be found in normal urine. 



In health the pigment is excreted in very small amount, and can 

 scarcely be said to function as an active colouring matter of the urine ; 

 but it is of the highest interest to recognise that this iron-free deriva- 

 tive of hsematin, which in the laboratory is only to be obtained by the 

 use of strong reagents, is a normal physiological product. In patho- 

 logical conditions, and especially after the use of certain drugs, it is 

 present in greatly increased amount. 



Isolation from normal urine. The method recommended by Garrod de- 

 pends upon the fact that the pigment is carried down by the precipitate of 

 phosphates produced on the addition of caustic alkali to the urine. After 

 special treatment of this precipitate, the pigment may be obtained in chloroform 

 solution. The chloroform is evaporated, and the residue washed with neutral 

 alcohol and dissolved in acidified alcohol, when a solution is obtained of pure 

 pink colour, comparable with solutions of the purest specimens of the pigment 

 obtained from blood, and showing the spectrum of acid hsematoporphyrin with 

 distinctness. 



l Sitzungsb. d. k. Akad. d. Wissensch., Wien, 1881, Bd. Ixxxiv. S. 536. 

 2 Proc. Roy. Soc. London, vol. xxxi. p. 206. 



3 Journ. PhysioL, Cambridge and London, 1892, vol. xiii. p. 598 ; ibid., 1894, vol. xvii. 

 p. 349. 



VOL. I. 40 



