COLORING MATTERS. 



93 



The organic coloring matters may be conveniently removed from 

 liquids containing them by the action of animal charcoal; that is, 

 carbon derived from the imperfect combustion of animal ^ibstances. 

 If a fluid containing either of the coloring matters be mixed with a 

 sufficient quantity of this charcoal and filtered, the filtered fluid will 

 pass through colorless. Albuminous substances are also retained upon 

 the filter when treated with animal charcoal ; while glucose and other 

 crystallizable and saline matters pass through freely in solution. 



The animal coloring matters most distinctly recognized are those of 

 the blood, the blackish-brown tissues, the bile, and the urine. 



FIG. 12. 



1. Hemoglobine, 



This is the coloring matter of the red globules of the blood, the 

 most abundant and important substance belonging to this group. 

 It forms much the largest 

 proportion of the solid ingre- 

 dients of the dried blood- 

 globules, and amounts to 

 from 25 to 30 per cent, of 

 their weight in the fresh 

 condition. It is also found, 

 in much smaller quantity, in 

 the substance of the muscu- 

 lar tissue, of which it forms 

 the coloring principle. It 

 crystallizes in well marked 

 forms, which vary somewhat 

 in different species of ani- 

 mals ; but are all, so far as 

 known, either rhombic or 

 hexagonal tables or prisms. 

 It is soluble in water, in very 

 dilute alcohol, and in dilute 

 solutions of albumen, of the alkalies, and their carbonates, and of 

 sodium and ammonium phosphates. It is insoluble in strong alcohol, 

 in ether, and in the volatile and fatty oils. In almost every condition 

 it is readily decomposed. According to Preyer,* crystals which have 

 been thoroughly dried at a temperature below the freezing-point become, 

 after a time, decomposed, and lose their color and solubility, even at 

 ordinary temperatures. A watery solution of hemoglobine kept at any 

 temperature above the freezing-point of water becomes altered in the 

 course of twenty-four hours, and if heated to 64 C. it is at once 

 decomposed. 



Hemoglobine, when crystallized, presents the bright red color of 

 arterial blood. It is distinguished beyond all other known ingredients 



HEMOGLOBINE CRYSTALS : from human blood. 

 (Punka) 



Die Blutkrystalle. Jena, 1871, p. 58. 



