234 HSEMATIN. 



To obtain pure hasmatin it is probably better to prepare it from haemin whose 

 purity as a mother substance can be ensured at the outset by the fact that, unlike 

 hfematin it is readily obtained in crystals. (See below.) The haemin crystals 

 should be boiled with strong acetic acid, then washed with water, alcohol, and 

 ether and dissolved in dilute caustic potash. The solution is then filtered, 

 precipitated with hydrochloric acid and washed with boiling water until the 

 washings are shown, as tested by nitrate of silver, to be free from hydrochloric 

 acid. The residue is finally dried by prolonged heating to 130 150. l 



For ordinary purposes hsematin is characterised chiefly by the 

 spectroscopic appearances of its solutions. When dissolved in an 

 alkali (ammonia, as in solution (c) above) it shows one absorption band 

 in the yellow adjoining D to the red side of this line, while at the 

 same time there is great absorption at the blue end of the spectrum 

 (Fig. 37, Nos. 1 and 2). On treatment with a reducing agent, Stokes' 

 fluid or ammonium sulphide, this band is replaced by two others in 

 the green of which the one nearest D is remarkably dense, the other 

 less sharply denned. Very little absorption of the red end is observed 

 while that of the blue is as before very marked (Fig. 37, No. 3). This 

 is the spectrum of Stokes' reduced hsematin and is identical with that 

 of Hoppe-Seyler's hsemochromogen. The two substances have usually 

 been regarded as identical, but this is disputed by Hoppe-Seyler (see 

 above). Alkaline solutions of hsernatin are strongly dichroic, being 

 ruby-red in thick layers and greenish in thin layers viewed by reflected 

 light. 



The acid alcoholic solution of hsematin (solution (b) above) is 

 characterised by one absorption band between C and Z>, adjoining C, 

 whose centre is situated at w. L. 640. This band is somewhat similar 

 to that of methsemoglobin, but it is less dense and careful observation 

 shows that the centres of the respective bands do not coincide (Fig. 37, 

 Nos. 5 and 4). Acid solutions of hsematin are monochromatic and oi 

 a dull reddish-brown colour. If blood or a strong solution of oxy- 

 hsemoglobin be made strongly acid by the addition of acetic acid the 

 hsemoglobin is decomposed, hsematin is set free, and if the solution be 

 shaken up with ether and allowed to stand, the ether rises to the 

 surface and is more or less coloured owing to the presence of hsematin 

 held in solution in the acid ether. This acid ethereal solution shows, 

 in addition to the one band already described as characteristic oi 

 heematin in an acid solution, three other bands whose positions and 

 relative intensities are sufficiently shown in Fig. 37, No. 6. 



Hsematin as prepared by the methods described above is usually 

 obtained as a scaly but not crystalline mass of bluish-black colour and 



1 Hoppe-Seyler, PhysioL pathol.-chem. Anal 5 Aufl. 1883, S. 239. See also Gaze- 

 neuve, These, Paris, 1876, Abstr. in Maly's Jahresb. 1876, S. 76. Bull. Soc. Chim 

 T. xxvn. (1877), p. 485. MacMunn, Jl. of PhysioL Vol. vi. 1884, p. 22. 



