26 H.KM1X AND BLOOD TESTS. 



Immiiiin m ttoid solution, which gives a spectrum with one absorption-band to the 

 red side of D near C (fig. 17, 5). There is at the same time a considerable 

 absorption of the blue end of the spectrum. If an ethereal extract of the acid- 

 hwmatin be made, the ether is coloured brown and shows four absorption-bands, 

 as in fig. 17, 5.] 



(2) Alkali-hsematin. [If to the above solution ammonia or caustic soda be 

 added, on heating gently, the colcur changes, and the fluid becomes dichroic, showing 

 a greenish tinge. On mixing the solution thoroughly with air the spectrum of 

 oxy-alkali-haematin is obtained, i.e., one absorption-band just to the red side of D 

 (fig. 17, G), so that it is much nearer D than the corresponding band of acid- 

 hsematin. Much of the blue end of the spectrum is absorbed as well.] 



[(3) Eeduced Alkali-hsematin or Hflemochromogen. If the solution of alkali- 

 haimatin be reduced by ammonium sulphide, the spectrum of hsemochromogen is 

 obtained, viz., two absorption-bands between D and E, but they are nearer the 

 violet end than in the case of Hb0 2 and Hb-CO (fig. 17, 7).] 



[(4) Haematoporphyrin or Iron-free Hsematin. On adding blood to con- 

 centrated sulphuric acid a clear purplish-red solution is obtained, which shows two 

 absorption-bands, one close to and on the red side of D, and a second half-way 

 between 1) and E. If water be added a brown precipitate is thrown down. When 

 this precipitate is dissolved in caustic soda, it gives a fluid which shows four 

 absorption-bands.] 



Action of CO.,. If CO., be passed through a solution of oxyhemoglobin for a considerable 

 time, reduced I lb is first formed. ; but if the process be prolonged the Hb is decomposed, a 



Crecipitate of globulin is thrown down, and an absorption-band, similar to that obtained when 

 [b is decomposed with acids, is observed (p. 25). 



An alkaline solution of hrematin, when reduced by tin and hydrochloric acid, 

 yields urobilin (compare S 261). 



When hemoglobin is extravasated into the subcutaneous tissue, it becomes so altered that 

 at first haematoidin ( 20), and ultimately hydrated oxide of iron, appear in its place. 



19. HJEMIN AND BLOOD TESTS. In 1853 Teichmann prepared crystals of 

 haemin from blood, which Hoppe-Seyler showed to be chloride of hsematin 



i+i* 



Fig. 18. 



Htemin crystals. 1, human ; 2, seal; 3, calf; 



4, pig ; 5, lamb ; 6, pike; 7, rabbit. 



(Ha3matin, + 2HC1), with the formula C 3 . 2 H 31 ClN 4 Fe03 (Neneki and Sieber). 

 The presence of these crystals is used as a test for blood-stains or blood in solution. 

 They (fig. 18) are prepared by adding a small crystal of common salt to dry blood 

 on a glass slide, and then an excess of glacial acetic acid ; the whole is gently heated 

 until bubbles of gas are given off. On allowing the preparation to cool, the 

 characteristic hajmin crystals are obtained. 



Characters. When well formed, the crystals are small microscopic rhombic 



