DERIVATIVES OF HEMOGLOBIN 125 



blood, and the solution boiled, the color alters to brown from decomposition 

 of hemoglobin and the setting free of hematin; by shaking this solution 

 with ether, a solution of hematin in acid solution is obtained. The spectrum 

 of the ethereal solution shows no less than four absorption bands, viz., one 

 in the red between C and D, one faint and narrow close to D, and then two 

 broader bands, one between D and E, and another nearly midway between 

 b and F. The first band is by far the most distinct, and the acid aqueous 

 solution of hematin shows it plainly. 



Hematin in Alkaline Solution. If a caustic alkali is added to blood and 

 the solution is boiled, alkaline hematin is produced, and the solution becomes 

 clive green in cclor. The absorption band of the new compound is in the 

 red, near to D, and the blue end of the spectrum is absorbed to a considerable 

 extent. If a reducing agent be added, two bands resembling those of oxy- 



FIG. 123. Hematoidin Crystals. (Frey.) FIG. 1233.. Hemin Crystals. (Frey.) 



hemoglobin, but nearer to the blue, appear; this is the spectrum of reduced 

 hematin, or hemochromogen. On violently shaking the reduced hematin 

 with air or oxygen the two bands are replaced by the single band of alkaline 

 hematin. 



Hematoidin. This substance is found in the form of yellowish crystals, 

 figure 123, in old blood extravasations and is derived from the hemoglobin. 

 Their crystalline form and the reaction they give with fuming nitric acid 

 seem to show them to be closely allied to Bilirubin, the chief coloring matter 

 of the bile, and in composition they are probably either identical or isomeric 

 with it. 



Hemin. One of the most important derivatives of hematin is hemin. 

 It is usually called Hydrochloride of Hematin, but its exact chemical com- 

 position is uncertain. Its formula is said to be C 32 H 30 N 4 FeO 3 HCl, and it 

 contains 5.18 per cent of chlorine, but by some it is looked upon as simply 

 crystallized hematin. Although difficult to obtain in bulk, a specimen may 

 be easily made for the microscope in the following way: A small drop of 

 dried blood is finely powdered with a few crystals of common salt on a glass 

 slide and spread out; a cover-glass is then placed upon it, and glacial acetic 

 acid added by means of a capillary pipet. The blood at once turns a brownish 

 color. The slide is then heated, and the acid mixture evaporated to dryness 



