NOTICE OF THE LIFE OF THE LATE PROFESSOR GRAHAM. 817 
In- the same year he became Lecturer on Chemistry at the Mechanics’ Institute, Glas¬ 
gow, and in the next year, 1830, achieved the yet more decisive step of being 
appointed Professor of Chemistry at the Andersonian University. By this appointment 
he was relieved from anxiety on the score of living; and afforded, in a modest way, the 
means of carrying out his experimental work. 
In 1831 he read, before the Royal Society of Edinburgh, a paper “On the Law of 
the Diffusion of Gases,” for which the Keith prize of the Society was shortly afterwards 
awarded him. Although several of his earlier papers, and especially that on the Diffu¬ 
sion of Gases, published in the ‘Quarterly Journal of Science,’ had given evidence of 
considerable power, it was this paper—in which he established the now well-recognized 
law that the velocities of diffusion of different gases are inversely as the square roots of 
their specific gravities—that constituted the first of what may properly be considered 
his great contributions to the progress of chemical science. 
In 1833 he communicated a paper, of scarcely less importance, to the Royal Society 
of London, entitled “ Researches on the Arseuiates, Phosphates, and Modifications of 
Phosphoric Acid.” It afforded further evidence of Mr. Graham’s quiet steady power of 
investigating phenomena, and of his skill in interpreting results ; or rather of his skill 
in setting forth the results in all their simplicity, undistorted by the gloss of precon¬ 
ceived notions, so as to make them render up their own interpretation. It is difficult 
nowadays to realize the independence of mind involved in Mr. Graham’s simple inter¬ 
pretation of the facts, presented to him in this research, by the light of the facts them¬ 
selves, irrespective of all traditional n.odes of viewing them. Their investigation let in 
a flood of light upon the chemistry of that day; and formed a starting-point from which 
many of our most recent advances may be directly traced. In this paper Mr. Graham 
established the existence of two new, and, at that time, wholly unanticipated classes of 
bodies, namely, the class of polvbasic acids and salts, and the class of so-called anhydro- 
acids and salts. The views of Graham on the polybasicity of phosphoric acid were soon 
afterwards applied by Liebig to tartaric acid, and by Gerhardt to polybasic acids in 
general, as we now recognize them. After a long interval the idea of poly basicity was 
next extended to radicals and to metals by Williamson and myself successively ; after¬ 
wards to alcohols by Wurtz, and to ammonias by Hofmann. The notion of anhydro- 
salts was extended by myself to the different classes of silicates; by Wurtz to the com¬ 
pounds intermediate between oxide of ethylene and glycol; and by other chemists to 
many different series of organic bodies. 
The next most important of the researches, completed by Mr. Graham while at 
Glasgow, was the subject of a paper communicated to the Royal Society of Edinburgh, 
in 1835, “ On Water as a Constituent of Salts,” and of a second paper communicated to 
the Royal Society of London, in 183G, entitled “ Inquiries respecting the Constitution 
of Salts,” etc., for which latter a Royal Medal of the Society was afterwards awarded. 
The subject of hydration had yielded him such a harvest of results in the case of phos¬ 
phoric acid, that it was only natural he should wish to pursue the inquiry further. In¬ 
deed, it is a curious illustration of the persistency of the man, that he never seems to 
have left out of sight the subjects of his early labours. Almost all his subsequent 
original work is but a development, in different directions, of his youthful researches on 
gas-diffusion and water of hydration ; and so completely did he bridge over the space 
intervening between these widely remote subjects, that, with regard to several of his 
later investigations, it is difficult to say whether they are most directly traceable to his 
primitive work on the one subject or on the other. 
In 1837, on the death of Dr. Edward Turner, Mr. Graham was appointed Professor 
of Chemistry at University College, London, then called the University of London. On 
his acceptance of this appointment, he began the publication of his well-known ‘ Ele¬ 
ments of Chemistry,’ which appeared in parts, at irregular intervals, between 1837 and 
1841. Elementary works, written for the use of students, have necessarily much in 
common ; but the treatise of Mr. Graham, while giving an admirably digested account 
of the most important individual substances, was specially distinguished by the character 
of the introductory chapters, devoted to Chemical Physics; wherein was set forth one 
of the most original and masterly statements of the first principles of chemistry that 
has ever been placed before the English student. “ The Theory of the Voltaic Circle ” 
had formed the subject of a paper communicated by Mr. Graham to the British Asso¬ 
ciation in 1839 j and the account of the working of the battery, given in his ‘ Elements 
