DERIVATIVES OF HEMOGLOBIN 



light until a shade is found with which it corresponds. For approxi- 

 mate results this method has proved very satisfactory. 



H 



FIG. 1220. Dare Hemoglobinometer. Instrument ready for use, illustration one- 

 half actual size. R, Milled wheel by which the color prism is rotated by friction exerted 

 upon its edge. S, Case enclosing color prism, showing stage upon which the blood 

 pipet slides. T, Movable wing pivoted to case. When drawn outward screens the 

 eyes of observer from the light. When not in use lies superimposed upon the circular 

 prism case, occupying no extra space. U, Telescoping camera tube in position for 

 examination. V, Opening in prism case, admitting light for illumination of color prism. 

 The white glass disc of prism is seen inside. W, White glass of blood pipet. X, Pipet 

 clamp held in position on the stage by grooves and guides. F, Detachable candle- 

 holder. Z, Rectangular opening in edge of case for reading hemoglobin percentage 

 indicated by beveled blade. L, Light (candle or electric.) Color prism. E, Prism of 

 colored glass. F, Semi-circle of white glass, the edge carrying the index of hemoglobin 

 percentage in black; this edge also serves as a friction surface for the rubber-covered roller 

 by which the prism is rotated. G, Hole in which hub is fixed. H, Index of hemoglobin 

 percentage etched in black. 7, Disc of white glass which serves to break the glare of 

 direct light and furnishes a white background to view the shades of color. 



Derivatives of Hemoglobin. Hematin. By the action of heat or 

 of acids or alkalies in the presence of oxygen, hemoglobin can be split up 

 into a substance called hematin, which contains all the iron of the hemo- 

 globin from which it was derived, and a protein residue, a histone, globin. 

 If there be no oxygen present, instead of hematin a body called hemochro- 

 mogen is produced, which, however, will speedily undergo oxidation into 

 hematin. 



Hematin is a dark brownish or black non-crystallizable substance of 

 metallic luster. Its percentage composition is C, 64.30; H, 5.50; N, 9.06; 

 Fe, 8.82; O, 12.32; which gives the formula C 68 H 70 N 8 Fe 2 O 10 (Hoppe- 

 Seyler). It is insoluble in water, alcohol, and ether; soluble in the caustic 

 alkalies; soluble with difficulty in hot alcohol to which is added sulphuric 

 acid. The iron may be removed from hematin by heating it with fuming 



