56 PHYSIOLOGICAL AND PATHOLOGICAL CHEMISTRY. 



from the rim, heat again and, after cooling, examine the slide 

 under the microscope. In case no hsemin crystals are found, 

 examine again after allowing to stand for a longer time. We 

 may also let a drop of blood dry on a piece of muslin, then 

 cut out the spot and boil this with glacial acetic acid, etc. 



XI. Haematoporphyrin. 



Hsematoporphyrin, according to Nencki and Sieber, 

 C 16 H 18 N 2 (^) 3 , 1 is formed from hsematin by warming the solution 

 of rurmin in glacial acetic acid saturated with hydrobromic 

 acid gas, according to the equation l 



C 32 H S2 N 4 Fe0 4 + 2HBr + 2H 2 = 2C 16 H 18 N 2 3 + FeBr 2 + H 2 . 



The anhydride, C 32 H 34 N 4 5 , is formed by the action of concen- 

 trated sulphuric acid upon haematin or haemoglobin. Add to 

 8 or 10 cc. of concentrated sulphuric acid, drop by drop, and 

 with constant shaking, five drops of blood. The clear red- 

 violet solution which results shows when examined with the 

 spectroscope two very beautiful and characteristic absorp- 

 tion-bands: a narrow band in the orange and a broader one 

 in the yellow and green (No. 6 in the Table of Absorption 

 Spectra). These show some resemblance to the bands of 

 oxy haemoglobin, but lie nearer to the red end of the spectrum. 

 The broad band is especially characteristic in that it consists 

 of two parts, a less intense part towards the narrow band and 

 a deep-black part on the other side; frequently the less in- 

 tense part of the broad band shows an edge towards the red, 

 which is marked by stronger absorption, so that we may also 

 speak of three absorption-bands in the spectrum. 



1 According to Zaieski the formula for haematoporphyrin hydrochloride 

 is C 34 H 38 O 6 X 4 -2HC1, and the formation of hsematoporphyrin from hirmin 

 is represented by the following equation: 



C 34 H 3 ,O 4 N 4 FeCl + 2HBr + 2H,O = C 34 H 38 O 6 N 4 + FeBr, + HC1. 

 Zeitschr. f. physiol. ("hem. 3", 74. O. 



