PEOFESSOR THOMAS GRAHAm's SCIENTIFIC WORK. 181 



years of age, bad produced, in addition to many less iiaportaiit eom- 

 niimicatioiis, iive principal memoirs ; three of them in the highest degree 

 successfnl ; the other two less successful in })roi»ortion to the expendi- 

 ture of time and labor on them, but, nevertheless, of great originality 

 and value. The most brilliant period, however, of his scientific career 

 was to come. In the year ISGl, and between then and his death in 18G9, 

 Mr. Graham communicated four elaborate papers to the Royal Society, 

 three of them far exceeding in novelty, interest, and ])hik)so-phic [)0wer 

 anything that he had before produced ; and the other of them, relating 

 to a certain physical effect of that hydration of compounds, from the 

 consideration of which his attention could never wholly be withdrawn. 

 This least important paper, "On liquid transpiration in relation to 

 chemical composition," was communicated to the lioyal Society in 1861. 

 Of the three greater papers, that " On li(piid <litfusion api)lied to anal- 

 ysis" was communicated also in 18G1. For this paper moie especially, 

 as well as for his Lakerian lectures "On the diffusion of liquids" and 

 "On osmotic force," Mr. Grahain received, in 1802, the Co[»ley medal 

 of the Royal Society; and, in the same year, was also awarded the 

 Jecker prize of the Institute of France. Following in quick succession, 

 his paper "On the molecular mobility of gases" was i)resented to the 

 Royal Society in 18G3 ; and that "On the absorption and dialytic 

 separation of gases by colloid septa," in 18G<). With regard to these 

 three great papers, two of them were each supplemented by a communi- 

 cation to the Chemical Society ; while the third was supplemented by 

 four successive notes to tbe Royal Society, containing an account of 

 further discoveries on the same subject, hardly less remarkable than 

 those recorded in the original paper. The last of these supplementary 

 notes was communicated on June 10, 18G1>, but a few months before the 

 death, on September lo, of the indefatigable but physically broken- 

 down man. 



In considering Mr. Graham as a chemical philosopher and lawgiver, 

 we find him characterized by a pertinacity of purpose peculiarly his 

 own. Wanting the more striking qualities by wliich his immediate pre- 

 decessors, Davy, Dalton, and Faraday, were severally distinguished, he 

 displayed a positive zeal for tedious quantitative work, and a wonder- 

 ful keen-sightedness in seizing the points which his innumeralde deter- 

 minations of various kinds, conducted almost incessantly for a period of 

 forty years, successively uniblded. His work itself was essentially that 

 of detail, original in conception, simple in execution, laborious by its 

 quantity, and brilliant in the marvelous results to which it led. As 

 regards its simplicity of execution, scarcely any investigator of recent 

 times has been less a friend to the instrument-nuiker than jMr. (Jraham. 

 W^hile availing himself, with much advantage, of appliances devised by 

 Bunsen, Poiseuille, Sprengel, and others, all the ap[)aratus introduced 

 by himself was of the simplest character, and for the most part of labor- 

 atory construction. 



