CHAPTER III 

 H.EMOCHROMOGEN 



xi^MOCHROMOGEN" and "reduced alkaline hsematin" have 

 been names hitherto attached on the one hand to a substance to 

 which the formula C34H3oN404Fe has been given and on the other 

 to a spectrum supposed to be the spectrum of that substance. Let 

 us say a word or two firstly about the formula and secondly about 

 the spectrum. 



The formula is that of a protein-free substance : it is closely allied 

 to haemin (C34H3oN404FeCl), and as there is no ambiguity about what 

 hsemin is let us start with it. Hsemin is a chloride, it is of course 

 obtained by acting on blood with glacial acetic acid and sodium 

 chloride, which reaction, if properly carried out, produces the crystals 

 known as Teichmann's crystals. These are crystals of hsemin and to 

 them is given the formula C34H3oN404FeCl. If the crystals are treated 

 with caustic soda a base is liberated with the formula C34H3oN404FeOH , 

 and this base when reduced yields C34H3oN404Fe — which has been our 

 conception of reduced alkaline haematin. To turn now to the spectrum, 

 one is always accustomed to tell students that the spectrum of 

 hsemochromogen can be seen in extremely dilute solutions of the 

 pigment. For this reason, among others, it is much sought after by 

 those who specialise in the pursuit of blood stains on rags. The stain 

 is extracted with caustic soda or potash, the coloured extract is 

 reduced, and if the reduced fluid shows the " haemochromogen " band 

 the stain is assumed to have been blood. 



The simple theory that haemochromogen, yielding the characteristic 

 spectrum, was the body C34H3oN404Fe obtained by the reduction of 

 hsematin C34H3oN404FeOH, has been found by several observers, 

 notably Bertin-Sans and Moitessier(i) and also Dilling(2), not to 

 represent the whole truth. 



They stated that during the reduction the presence of some nitro- 

 genous body was necessary: what role this nitrogenous body played, 

 whether it was a catalyst or a substance which entered in some more 

 definite way into the reaction, was not stated by Bertin-Sans and 

 Moitessier. Dilling was more explicit. He published his work in 

 the form of a rather elaborate monograph, printed in English and 

 in German with the same cover, and his spectroscopic constants 



