504 Prof. A. Gamgee. On the Behaviour of Oxy-hcemogldbin, 



for all the substances of which he is formed, including the blood, 

 possess this property." * 



De la Eiveand Brunner,f later, suspending a bound-up frog between 

 the poles of an electro-magnet, observed it to assume an equatorial 

 position, thus realising Faraday's prediction that a complex animal 

 organism must be diamagnetic in accordance with the properties of its 

 constituent tissues and of the water which enters so largely into their 

 composition, 



Shortly after the publication of Faraday's researches on dia- 

 magnetism, Professor Pliicker,t of Bonn, in a well-known paper, which 

 appeared in 1848, after describing the characteristic behaviour of 

 magnetic and diamagnetic liquids contained in watch-glasses placed 

 upon and between the poles of powerful electro-magnets, gave the 

 results of his observations on the diamagnetic properties of the blood. 

 He not only coDfirmed, by experimenting on the blood of the frog, of 

 man, and of the ox, the accuracy of Faraday's statements, but, by 

 employing the microscope in his observations, he was able to show 

 that the blood corpuscles are more strongly diamagnetic than the 

 liquid in which they float.§ 



2. Objects of the Present Investigation. 



At a time when all facts bearing on the physical properties and the 

 chemical relations and structure of the blood-colouring matter are 

 rightly claiming the attention of many of the leading workers in 

 physiological chemistry, it appeared to me very desirable to examine 

 the magnetic properties of the crystalline blood-colouring matter itself, 

 in the condition of utmost available purity, and, whatever the results 

 might be, to extend the inquiry to its leading iron-containing deriva- 

 tives. 



* Faraday's 'Experimental Eesearclies in Electricity,' vol. 3, p. 36 (2281). 



f De la Bive and Br miner's researches are only known to me at second hand 

 from the account given of them in Valentin's ' Grunclriss der Physiologie ' 

 (4 Auflage, 1855, p. 507), where an engraving is reproduced in which a bound-up 

 frog is shown placed between the poles of an electro -magnet. 



X Plucker, ' Experimentelle Untersuchungen uber die Wirkung der Magnete auf 

 gasformige und tropfbare Flussigkeiten.' Eefer to the heading "Uber das 

 magnetische und diamagnetische Verhalten der tropf barflussigen Korper," in 'Pog- 

 gendorff's Annalen der Physik und Chemie,' vol. 73, 1848, p. 575, para. 49. 



§ In 1874, Dr. E. C. Shettle, in a paper read before the Eoyal Society ('Boy. 

 Soc. Proc.,' vol. 23, 1875, pp. 116—120), gave the results of experiments which 

 had led him to the conclusion that arterial blood is paramagnetic as compared 

 with venous blood, which is diamagnetic, the assumed difference in magnetic 

 behaviour being explained by the author as due to the paramagnetic properties of 

 the oxygen absorbed by venous blood. In reference to these statements, the only 

 observation which I have to make, on the basis of my own work, is that they are 

 entirely erroneous. 



