CHAP. II.] THE BLOOD. 109 



Methaemoglobin. 



spectrum When a solution of haemoglobin is exposed to air 



of Methaemo- f or some time it loses its blood-red colour, assumes a 

 brownish tinge, presents an acid reaction, is precipi- 

 tated by solutions of basic lead acetate, and on examining its 

 spectrum it is found that the two bands of oxy-haemoglobin have 

 become faint, and that a new band has appeared in the red near C ; 

 this line occupies nearly though by no means exactly the position of a 

 similar band in the spectrum of acid haematin. On now rendering 

 the solution alkaline by the addition of ammonia, the band in the red 

 disappears, and is replaced by a faint absorption band immediately 

 near D. 



The most remarkable phenomenon, however, relates to the action 

 of reducing agents. 



If to a solution which exhibits the last - mentioned spectrum 

 there be added some sulphide of ammonium, it is observed that it 

 manifests the spectrum of reduced haemoglobin. On shaking the so- 

 lution containing the latter with air, oxy-haemoglobin is again formed. 



Production The peculiar and remarkable properties above mentioned 



of methaemo- were described by the Author in 1867 1 and more fully in 

 S b ii,!! 1868 > as developed by the action of nitrites on solutions of 

 haemoglobin and upon blood. It was shewn that besides 

 presenting the remarkable optical properties and reactions 

 previously referred to, as a result of the action of nitrites, the respiratory- 

 . oxygen of haemoglobin had become irremovable by carbonic oxide or in a 

 Torricellian vacuum, but that after undergoing the change the haemoglobin 

 could be crystallized repeatedly, the body thus produced only differing from 

 oxy-haernoglobin by its colour and its spectrum. On analysis it was found that 

 the crystalline compound always retained some of the nitrite used, and the 

 view was therefore expressed that in all probability the action exerted by ni- 

 trites consisted in the formation of a compound of those bodies with oxy-hae- 

 moglobin, which compound was decomposed by the reducing agent employed. 

 It was subsequently observed by Sorby 2 , Lank ester 3 , and Jaderholm 4 

 that Gamgee's nitrite-haemoglobin spectra coincided with those of methae- 

 moglobin prepared by the action of potassium permanganate, and the 

 presumption has been established that his bodies really consisted of 

 methaemoglobin generated by the action of nitrites. This change in the 

 view as to the nature of the bodies produced under the influence of 

 nitrites does not however affect the facts established by the researches 

 above referred to. According to Sorby, however, methaemoglobin would 

 be a per-oxy-haemoglobin, i.e. a more highly oxygenized haemoglobin, 



1 Gamgee, "Note on the action of nitric oxide, nitrous acid and nitrites on 

 Haemoglobin." Proceedings of the Royal Society of Edinburgh, 1867, p. 168. " On 

 the action of nitrites on blood." Philosophical Transactions, 1868, pp. 589 625. 



2 Sorby, Quarterly Journ. of Micros. Sc. 1870, p. 400. 



8 Lankester, " Abstract of a Keport on the Spectroscopic Examination of certain 

 animal substances." Journal of Anat. and Phys. Vol. iv. p. 123. 



4 Jaderholm, " Untersuchungen uber den Blutfarbstoff und dessen Zersetzungs 

 producte," Abstracted from the original Swedish by Hammarsten in Maly's Jahres- 

 bericht t Vol. vi. p. 85. 



