Annual Report of the Council. liii 



Henry Enfield Roscoe, the son of Henry Roscoe, a 

 barrister, of Liverpool, was horn in London in 1833. He was 

 the grandson of William Roscoe, a hanker in Liverpool, well 

 known as the author of the Life of Lorenzo de 1 Medici. Roscoe's 

 mother was the daughter of a Liverpool merchant named 

 Fletcher and the granddaughter of Dr. William Enfield, Rector 

 of Warrington Academy, where Joseph Priestley taught chemistry. 

 He was educated at the Liverpool Institute, and was taught 

 chemistry by W. H. Balmain, the inventor of : ' luminous paint." 

 His education was continued at University College, London, 

 where he came under the influence of Thomas Graham, and 

 subsequently of A. W. Williamson, who succeeded Graham in the 

 chair of chemistry. Leaving London he proceeded to Heidelberg 

 to study under Bunsen, and there began a life-long friendship 

 and a close association in scientific investigation with that 

 eminent chemist. After taking his degree, Roscoe joined 

 Bunsen in a prolonged research on the chemical intensity of 

 light and on a method for determining its amount. Their first 

 method was founded on the well-known fact that chlorine and 

 hydrogen when mixed together and exposed to light, combined 

 together, with formation of hydrochloric acid easily soluble in 

 water. The apparatus used for this investigation served to prove 

 several points of great interest among others, that the amount 

 of chemical action occurring from a constant source, varied 

 inversely as the square of the distance. By means of it they 

 also showed the effect of the different parts of the spectrum on 

 the rate of combination of the two gases. Their second method 

 depended on the observation of the amount of darkening occurring 

 in specially prepared photographic paper and comparing it after 

 exposure to light wij:h standard tints. The apparatus required 

 for this purpose was simpler and more portable than that of the 

 first method and much more generally applicable. More than 

 seven years were occupied in this research, the results of which 

 are recorded in the Philosophical Transactions. 



Leaving Heidelberg, Roscoe settled in London and estab- 

 lished a private laboratory, having Wilhelm Dittmar as his 



