THE GREAT LONDON CHEMISTS 65 



porous diaphragm, such as the common acids and salts, 

 from ' colloid ' or gum-like substances, the rate of passage 

 of which is much slower. Especially useful was this pro- 

 cess for the separation of poisons such as the alkaloids 

 and metallic salts from the contents of the stomach in 

 medico-legal inquiries. 



Time allows me only to mention Graham's most in- 

 teresting experiments on the absorption of gases by 

 metals, and the passage of hydrogen through a thin sheet 

 of palladium; the retention of hydrogen by palladium 

 led him to surmise that the metallic substance was a 

 true alloy of palladium, with metallic hydrogen, and to 

 form the theory that hydrogen itself should be ranked 

 among the metals. He even tried to impress the view by 

 terming the element ' hydrogenium,' in consonance with 

 the nomenclature of most metals. 



But I must conclude this imperfect sketch of Graham's 

 work, trusting that what I have said may induce some of 

 my readers to make acquaintance with it at first hand. 

 Graham's conscientiousness in all he did, his enthusiasm, 

 and his great ability render his style in writing a most 

 fascinating one; and his papers will always remain a 

 model to those who publish on similar subjects. He 

 possessed a truly philosophical mind ; and in this he more 

 resembled Boyle, than Cavendish or Davy. Indeed, it 

 may be guessed that if Graham had lived in the seven- 

 teenth century, and Boyle in the nineteenth, the results of 

 their labours would not have differed very widely from 

 those which bear their respective names. 



Contrasting Graham's character with those of Cavendish 

 and Davy, it may be said that while Cavendish carried his 

 devotion to science to such a height that it deprived him of 

 the ordinary pleasures of a human being, and while Davy 

 took perhaps too prominent a part in the world of fashion 



E 



