PEOFESSOR THOMAS GRAIIAm's SCIENTIFIC WORK. 179 



Eoyal Society of Edinburgii, in 1835, " On water as a constituent of 

 salts," and of a second paper communicated to the Eoyal Society of 

 London, in 1830, entitled "Inquiries respectiugthe constitution of salts, 

 &c.," for which latter a royal medal of the society was afterward 

 awarded. The subject of hydration had yielded him such a harvest of 

 results in. the case of phosphoric acid, that it was only natural he should 

 wish to pursue the inquiry further. Indeed, it is a curious illustration 

 of the persistency of the luan that he never seems to have left out of 

 sight the subjects of his early labors. Almost all his subsequent 

 original work is but a development, in different directions, of his youth- 

 ful researches on gas-diffusion and water of hydration; and so com- 

 pletely did he bridge over the space intervening between these widely 

 remote subjects, that, with regard to several of his later investigations, 

 it is diilicult to say whether they are most directly traceable to his primi- 

 tive work on the one subject or on the otber. 



In 1837, on the death of Dr. Edward Turner, Mr. Graham was ap- 

 pointed professor of chemistry at University College, London, then 

 called the University of London. On his acceptance of this appoint- 

 ment he began the publication of his well-known Elements of Chem- 

 istry, which appeared in parts, at irregular intervals, between 1837 and 

 1811. Elementary works, written for the use of students, have neces- 

 sarily mucli in common ; but the treatise of Mr. Graham, while giving 

 an admirably digested account of the most important individual sub- 

 stances, was specially distinguished by the character of the introductory 

 chapters, devoted to cbemical physics, wherein was set forth one of 

 the most original and masterly statements of the first principles of chem- 

 istry that has ever been placed before the English student. " The 

 theory of the voltaic circle" had formed the subject of a paper com- 

 municated by Mr. Graham to the British Association in 1839 ; and the 

 account of the working of the battery, given in his Elements of Cbem- 

 istry, and based on the above paper, will long be regarded as a model of 

 lucid scientific exposition. 



In 1811 the now flourishing Chemical Society of London was founded ; 

 and though Mr. Graham had been, at that time, but four years in Lon- 

 don, such was the estimation in which he was held by his brother chem- 

 ists, that he was unanimously- chosen as the first president of the society. 

 The year 1844 is noticeable in another way. Wollaston and Davy had 

 been dead for some years. Faraday's attention had been diverted from 

 chemistry to those other branches of experimental inquiry in which his 

 highest distinctions were achieved ; and, by the death of Dalton in this 

 year, Mr. Graham was left as the acknowledged first of English chem- 

 ists, as the not unworthy successor to the position of Black, Priestley, 

 Cavendish, Wollaston, Davy, and Dalton. 



From the period of his api)ointment at University College, in 1837, , 

 Mr. Graham's time was fully occupied in teaching, in writing, in advising 

 ou chemical manufactures, in investigating fiscal and other questions for 



