238 PROCEEDINGS OF THE AMERICAN ACADEMY 



But besides having these practical applications, the method of dialysis 

 in the hands of Graham yielded the most startling results, developing an 

 almost entirely new class of bodies as the colloidal forms of our most 

 familiar substances, and justifying the conclusion that the colloidal as 

 well as the crystalline condition is an almost universal attribute of 

 matter. Thus, he was able to obtain solutions in water of the colloidal 

 states of aluminic, feoric, chromic, stannic, metastannic, titanic, molybdic, 

 tungstic, and silicic hydrates, all of which gelatinize under definite 

 conditions like a solution of glue. The wonderful nature of these facts 

 can be thoroughly appreciated only by those familiar with the subject, 

 but all may understand the surprise with which the chemist saw such 

 hard, insoluble bodies as flint dissolved abundantly in water and con- 

 verted into soft jellies. These facts are, without doubt, the most im- 

 portant contributions of Dr. Graham to pure chemistry. 



In this sketch of the scientific career of our late Associate, we have 

 followed the logical, rather than the chronological, order of events, 

 hoping thus to render the relations of the different parts of his work 

 more intelligible. It must be remembered, however, that the two lines 

 of investigation we have distinguished were in fact interwoven, and 

 that the beautiful harmony which his completed life presents was the 

 result, not of a preconceived plan, but of a constant devotion to truth, 

 and a childlike faith, which unhesitatingly pressed forward whenever 

 nature pointed out the way. 



Although the investigations of the phenomena connected with the 

 molecular motion in gases and liquids were by far the most important 

 of Dr. Graham's labors, he also contributed to chemistry many re- 

 searches which cannot be included under this head. Of these, which 

 we may regard as his detached efforts, the most important was his 

 investigation of the hydrates and other salts of phosphorus. It is true 

 that the interpretation he gave of the results has been materially modi- 

 fied by the modern chemical philosophy, yet the facts which he estab- 

 lished form an important part of the basis on which that philosophy 

 rests. Indeed, it seems as if he almost anticipated the later doctrines of 

 types and polybasic acids, and in none of his work did he show more 

 discriminating observation or acute reasoning. A subsequent investi- 

 gation on the condition of water in several crystalline salts and in the 

 hydrates of sulphuric acid is equally remarkable. Lastly, Graham also 

 made interesting observations on the combination of alcohol with salts, 

 on the process of etherification, on the slow oxidation of phosphorus, 



