114 THE BLOOD. 



HEMATIN AND H^EMIN. 



Haematin is the iron compound which is combined 

 with an albuminous substance to form oxyhaemoglobin. 

 It is set free whenever oxyhaemoglobin is decomposed by 

 the action of the gastric or pancreatic juice or by an acid. 

 It is consequently found in the intestine after the eating 

 of meat; also in the stomach after poisoning by a mineral 

 acid. 



The formula is given as: 



C 34 H 35 N 4 Fe0 5 or C 32 H 32 N 4 Fe0 4 . 



It may be obtained from haemin, its compound with hy- 

 drochloric acid. It is an amorphous substance, dark brown 

 or bluish black. 



Hsemin is composed of haamatin and hydrochloric 

 acid, probably one molecule of each. It forms micro- 

 scopic crystals which, in a large amount, have a blue- 

 black color. Under the microscope they are brown, rhom- 

 bic prisms. They are sometimes separate, but two are often 

 crossed or several are collected in clusters or rosettes. 

 (Plate I, 3.) They are insoluble in water, but dissolve 

 in alkalies, the haBmatin being set free. They are often 

 called Teichmann's crystals, and are important in proving 

 the presence of blood. 



CARBONIC OXID HEMOGLOBIN. 



When carbonic oxid, either pure or mixed with other 

 gases, is breathed or passed through blood, it unites with 

 the hemoglobin, forming CO-hsemoglobin: a compound 

 similar to oxyhaemoglobin. It is, however, a more stable 

 compound, the oxygen being unable to drive out the CO 



