1896.] Violet and ultra- Violet Rays by Hcemoglobin, 4'°' 277 



facts, employing the photographic method in his experiments. Since 

 the date of the publication of Soret's short notes on this subject, 

 d'Arsonval* has independently, and without referring to Soret's 

 observations, described anew the extreme violet absorption band of 

 the blood-colouring matter, but without adding to the facts discovered 

 by the Swiss observer. 



The complete absence of all reference to Soret's scanty, but 

 interesting and suggestive, observations, in text-books and treatises 

 on physiology and physiological chemistry, the fact, which my obser- 

 vations soon elicited, that the absorption band of Soret is much more 

 distinctive of the blood-colouring matter than the absorption bands 

 in the visible spectrum which have hitherto engrossed the attention 

 of observers, led me to interest myself in an investigation which 

 promises to throw much light on the relations of the blood-colouring 

 matter to other organic proximate principles, and on the transforma- 

 tions which the blood-colouring matter undergoes in the animal 

 economy. 



In this paper it is* my object merely to communicate some of the 

 more interesting results which I have hitherto obtained, a full dis- 

 cussion of the details of the research, which are of special interest 

 to physiologists and physiological chemists, being reserved for future 

 publication. 



My observations have, for the most part, been carried out with the 

 aid of a spectrometer furnished with a quartz prism and quartz 

 lenses, and the observations were made with the help of photo- 

 graphy. 



The substances which will be referred to in the statement of 

 results are the following : — 



1. Oxy-haemoglobin. 2. Haemoglobin. 3. The CO- and NO-com- 

 pounds of Haemoglobin. 4. The iron-containing products of decom- 

 position of haemoglobin and of oxy-haemoglobin, viz., Haemochromogen 

 (reduced haematin) and Haematin. 5. Metheemoglobin. 6. Haemato- 

 porphyrin. 7. Bilirubin, Hydro bilirubin, and Urobilin. 



The following are some of the principal results of the investiga- 

 tion : — 



I. The compounds of haemoglobin with oxygen, carbonic oxide, and 

 nitric oxide present, even in highly dilute solutions, an absorption 

 band between Fraunhofer's lines Gr and H. As a result of a large 

 number of measurements, I conclude that in the case of oxy-haemo- 

 globin the mean ray absorbed coincides with \ 414*0, that is to say, 

 the centre of absorption is slightly nearer the red end of the spectrum 

 than Soret had stated ; this observer placed the centre of absorption 

 at h (X 4101). 



* A. d'Arsonval, 'Arch, de Physiologie Norm, et Patholog.,' 5me serie, vol. 2 

 (1890), pp. 340—346. 



