400 



On same Compounds derived from the Colouring Matter 

 of Blood. By H. C. Sorby, F.R.S., &c. 



Several months ago I determined to thoronghly investi- 

 gate the colouring matter of blood, in order to be able to 

 ajjply to the detection of blood-stains all the imj)rovcd 

 methods of experiment Avhich I had devised since the publi- 

 cation of my first paper on that subject.^ I anticipated 

 being able to finish this inquiry in time to publish an 

 account of my observations in this number of the ' Quarterly 

 Journal of Microscopical Science,' but so many unexpected 

 phenomena presented themselves that I have not yet been 

 able to clear ujd several important questions. HoAvever, not 

 wishing to entirely postpone the subject for another three 

 months, I will now give a short account of some of my 

 conclusions. 



In the first place, I have found that one of the chief sub- 

 stances met with in moderately old blood-stains, previously 

 described by me as " brown cruorine," is identical with that 

 formed by adding nitrites to blood, as discovered by Dr. 

 Gamgee." 



Hoppe-Seyler's ^ and Preyer's ^ " metha>moglobin " is also 

 in some cases this same compound, but in others Avas perhajjs 

 chiefly a soluble, almost neutral, ha^matin. They considered 

 it to be characterised merely by the position of an absorption- 

 band in the red of its spectrum, not being acquainted Avitli 

 the fact that the position of the chief band in case of acid 

 hajmatin varies to a remarkable extent, according to the 

 strength of the free acid, and not having observed several of 

 the more important peculiarities of the well-defined compound 

 to which I now draw attention. Dr. Gamgee thought it due 

 to a combination of haemoglobin with nitrites as such, but I 

 have been led to conclude that they do not combine Avith it, 

 but act like many other Aveak oxidizing reagents. Nitrite of 

 potash is, indeed, a most useful substance in studying the 

 spectra of many colouring matters. Usually it has no effect 

 when added to a solution made alkaline Avith ammonia, but 

 produces most interesting changes AA'hen the solution is 

 neutral or slightly acid. This is just Avliat occurs in the 

 case of blood. It causes no change Avhen the solution con- 



1 ' Quarterly Journal of Science,' 1S65, vol. ii, p. 205. 



2 'Pliilosopliical Trans, of Hoy. Soc.,' 18G8, p. 5S9. 



3 'Zeitsclirift fiir Chiniie,' 18G5, p. 218. 



* 'Archiv fiir die gcsamte Pliysiologie,' 1868, p. 395. 



