HjEMATIN. 303 



of a solution of sulphate of soda or chloride of sodium, filter it, and 

 wash the residue on the filter as thoroughly as possible with the same 

 saline solution ; the residue thus almost completely freed from serum, 

 or, in other words, the mass of the blood-corpuscles, is dissolved 

 in water, and coagulated by the application of heat ; the washed, 

 dried, and finely triturated coagulum is now boiled with spirit con- 

 taining sulphuric acid, till the fluid passes through a filter in a 

 decolorised state. This filtered fluid, which in the mass presents 

 a brownish-red tint, after being saturated with ammonia, deposits 

 sulphate of ammonia and a little globulin; these being removed 

 by filtration, the fluid is evaporated to dryness ; the solid residue is 

 extracted with water, alcohol, and ether, and in order to effect the 

 complete removal of any adhering globulin, is again dissolved in 

 spirit containing ammonia; the solution is then filtered, evapo- 

 rated, and the residue extracted with water. 



Tests. If from any suspicion of the presence of blood we wish 

 to examine a fluid for hsematin, it is by far the best plan to employ 

 the microscope, and by its means to endeavour to detect blood- 

 corpuscles, or their fragments. It only rarely happens, in certain 

 exudations or saturated masses in which blood-corpuscles are no 

 longer present, that we can with certainty recognise the red pigment 

 of the blood, since its quantity is so small, that we can scarcely 

 obtain enough, by the methods we have given, to apply any tests 

 to it. 



That the hdematoidin discovered, or at least first accurately 

 investigated by Virchow,* (the same substance which has also been 

 named xanthose) is not perfectly identical with hsematin is obvious 

 from Virchow's experiments ; but the occurrence of this substance 

 in sanguineous extravasations, whose metamorphoses have been 

 most admirably traced out by Zwicky, Bruch, and Virchow, denotes 

 as decidedly as chemical experiments could do, that it is formed 

 from hsematin ; moreover, several of its properties indicate its close 

 affinity with the last named substance. 



H&matoidin occurs in an amorphous condition in granules, 

 globules, and jagged masses, as well as in perfectly formed crystals 

 of the monoclinometric system ; these latter are oblique rhombic 

 prisms, not unlike crystals of gypsum, but frequently are almost per- 

 fect rhombohedra ; they are strongly refractive and transparent, are 

 of a yellowish-red, red, or ruby colour, and are insoluble in water, 

 alcohol, ether, acetic acid, dilute mineral acids, and alkalies. I 

 have sometimes seen the smaller and less deeply coloured crystals 

 * Arch. f. pathol. Anat. u. s. w. Bd. I, S. 383-415. 



