122 Memoir of Thomas Graham. 



the conclusion that the colloidal as well as the crystalline con- 

 dition is an almost universal attribute of matter. Thus, he was 

 able to obtain solutions in water of the colloidal states of alu- 

 minic, ferric, chromic, stannic, metastannic, titannic, molybdic, 

 tungstic, and silicic hydrates, all of which gelatinize under defi- 

 nite 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 converted into soft jellies. 

 These facts are, without doubt, the most important contrik- 

 tions 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 tlie 

 '"■■" ■ ■ — • - - \Y\^\i\%. It : ■ " - 



harmony which his completed life presents was the result, not 

 of a preconceived plan but of a constant devotion to truth, and 

 a child-like faith, which unhesitatingly pressed forward when- 

 ever nature pointed out the way. 



Although the mvestigations 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 researches 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 modified by the 

 modern chemical philosophv, yet the facts which he estabhshed 

 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 reason- 

 ing. A subsequent investigation on the condition of water m 

 several crystalline salts and in the hydrates of sulphuric acid is 

 equally remarkable. Lastly, Graham also made interesting ob- 

 servations on the combination of alcohol with salts, on the 

 process of etherification, on the slow oxidation of phosphorous, 

 and on the spontaneous inflammability of phosphuretted hydro- 

 gen. It would not, however, be appropriate in this place to do 

 more than enumerate the subjects of these less hnportant 

 studies ; and we have only aimed in this sketch to give a gene- 

 ral view of the character of the field which this eminent student 

 of nature chiefly cultivated, and to sliow how abundant was the 

 harvest of truth which we owe to his faithful toil. 



