CHEMICAL EXAMINATION OF THE BLOOD. 349 



hematoporphyrin, which is isomeric with bilirubin. This change is 

 expressed in the equation : 



C 32 H 32 N 4 4 Fe + 2H 2 - Fe = = C 32 H 36 N 4 O 6 

 Hsematin Bilirubin 



(hsem atoporphy rin ) . 



Bilirubin, according to Kiister, yields the same acids on oxida- 

 tion as haematin or at least isomeric bodies. The intimate connec- 

 tion existing between the blood-pigment and bile-pigment, and 

 through this with the urinary pigment, is thus satisfactorily estab- 

 lished. 



The various data further permit an insight into the more intimate 

 structure of the haematin molecule. It may thus be inferred that 

 haematin consists of two symmetrical halves which are united by 

 iron. Since both haematin and haematoporphyrin yield the same 

 quantity of the same hsematinic acid, and since the latter each 

 contain 8 carbon atoms it suggests itself that hsematoporphyrin in 

 turn consists of two symmetrical halves. Accordingly the struc- 

 ture of haemin could be viewed as shown in the formula : 



CH S .C^C.CH = C(OH)-C = C CH = CH C C CH, 



il II II II II 



HC CH O FeCl HC CH 



\'H YH 



3.0 C.CH = C(OH C = C-CH = CH C C- 



CHrC-GGH = C(OH C = C-CH = CH C C CH S 



II II II II 



HC CH HC CH 



\/ \/ 



NH NH. 



On reduction with tin and hydrochloric acid in alcoholic solution 

 and the subsequent addition of caustic alkali in excess haematin 

 gives rise to skatol. On intense oxidation with ammonium persul- 

 phate cyanic acid and succinic acid result. 



As haematin is a decomposition-product of oxyhaemoglobin it 

 is not found as such in the circulating blood. It is said to occur in 

 the urine, however, in cases of poisoning with arsenious hydride. 

 In the stools it is found after hemorrhages into the stomach or the 

 upper portion of the small intestine, and also after the ingestion of 

 large amounts of red meats. In such cases, of course, its origin is 

 referable to the decomposition of haemoglobin through the agency of 

 the gastric and pancreatic juices. 



Hsemin. Hsemin has been generally regarded as haematin hydro- 

 chlorate and formed through the direct apposition of hydrochloric 

 acid. But as Nencki already suggested it is more likely that the 

 HC1 replaces an OH group : 



C 32 H 32 N 4 FeO 4 + HC1 = C 32 H 31 ClN 4 FeO 3 + H 2 O 

 Hsematin. Hsemin. 



Very curiously elementary analysis of the substance has given the 

 same results to the same observer, but different results to different 



