COLLOIDS in BIOCHEMISTRY* An A p p r e c i a t i o n of Thomas Graham
ROSS AIKEN GORTNERt The University of Minnesota, St. Paul, Minnesota
Thomas Graham (1805-1869) has been rightly called the father of colloid chemistry, but his works are so widely scattered through various periodicals and copies of his "Collected Works" are so rare that apparently very few people have taken the rouble to read all of the papers which he published in various scientific periodicals. A careful perusal of these papers reereals the fact that Graham's interest in colloid chemistry g r m out of his studies on diffusion, and that i n h k forty-six published papers he had but a single objective, namely the elucidation of the phe-
nomena underlying the process of diffusion. Apparently Graham spoke a language wltich was but little understood by his contemporaries, and for that reason many of his obsemations were either ooerlooked or ignored. In all of his published papers are many comments on the effect of chis or that particular phenomenon on life processes, and this paper i s designed to call attention to some of the outstanding statemats and contributions which Graham made in the field of colloid chemistry as applied to h&g processes.
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Contemporary with the fathers of organic chemistry (Wohler, 1800-1882; Liebig, 1803-1873) another chemist was blazing new trails. Thomas Graham was born December 21, 1805, and died September 16, 1869. His researches lay almost exclusively in the field of physical chemistry, although he had died before any of the physical chemistry triumvirate had begun to publish. If anyone can be truly said to be the father of physical chemistry, that credit should go to Thomas Graham. A perusal of his collected papers.' comprising 46 titles in all, reveals a continuity in objectives, a persistence in following up details, a scientific imagination far in advance of his time, an ability in apparatus technic, and an uncanny clearness of interpretation of experimental data, all of which leaves the reader more and more amazed a t the things which he accomplished and the views which he expressed. It is no wonder that the name and works of Thomas Graham have not received the credit which they deserve. He lived and thought so far in advance of his time that full appreciation could only come after the passage of many years, and even today this remarkable man does not receive the credit which I believe is his due. Graham has been rightly called the "Father of Colloid Chemistry." His Bakerian lecture "On the Diffusion of liquid^,"^ delivered Dec. 20, 1849, and which required seventy-eight printed pages (a lecture which would probably be unduly long for our modern audiences) may be regarded as the beginning paper in colloid chemistry. However, it is only the summary, and the philosophical discussion, of his researches on diffusion which began with his first paper, at the age of
HE CENTURY OF PROGRESS EXPOSITION is one of the factors wbich induced the chemists to hold the fall meeting of the American Chemical Society in Chicago. For chemical science it certainly has been a centnry of progress, for it was only a little over a hundred years ago (1828) that Wohler synthesized urea from ammonium cyanate and demonstrated for the first time that a vital force was not necessary for the formation of "organic" compounds. Organic chemistry had its beginnings in biochemistry, and the early organic chemists were intensely interested in the chemistry of the fats, carbohydrates, pigments, proteins, etc. In the majority of cases, however, the naturally occurring organic compounds proved to be too complex for the earlier organic technics, so that "pure" organic chemistry turned aside to study synthetic reactions and group behavior. Only recently have the leaders in organic chemistry returned to the original plan, and the acclaim which greets such names as Willstatter, Hans Fischer, Windaus, and Karrer attests the success which is being made in the structural chemistry of compounds formed by living organisms. It is much less than a century ago that the great triumvirate of van't Hoff (1882-1911), Ostwald (18531932). and Nernst (1864) is credited with laying the foundations of modern physical chemistry. What a structure has been erected thereon! The progress of onr present material civilization is in no small measure due to the developments in physical chemistry and its ally-applied physics. On every hand we meet with the comforts,~conveniencesand, we now believe, necessities that have grown from the applications of the knowledge gained in research in physical chemistry.
* Presented at the "Symposium on the Century of Progress in Colloid Chemistry" at the Chicago meeting of the American Chemical Society, Colloid Division, Tuesday. September 12, 1933. t Professor of Agricultural Biochemistry. 27
21, entitled "On the Absorption of Gases by Liquids,"% which paper led rapidly into his studies of diffusion, first with gases in 182g4and later with liquids and finally culminated with his papersin 1861entitled "Liquid Diffusion Applied to Analysis" which is essentially modern in its colloid terminology and colloid-chemical viewpoint. In almost every paper of Graham's we find that he is investigating the phenomena of diffusion, and in following wholeheartedly this one objective in all of its ramifications he uncovered fact after f a d so that when the proper time came his conception of the colloidal state of matter rested upon a fnm experimental foundation. I am supposed to speak on "Colloids in Biochemistry" hut I believe the purpose of this symposium will he better served by the devotion of the major portion of my time to calling attention to some remarkable comments which Graham made regarding colloid chemistry in general and especially the rBle of colloids in living processes. In 1830, when Graham was only twenty-five years old, he published a paper in the Quarterly Journal of Science,( entitled "The Effects of Animal Charcoal on Solutions." This paper is an outstanding contribution in the field of adsorption. He notes that bone black had already been used to decolorize sirups in the process of sugar manufacture, hut that hitherto the only study which had been made of bone black was in connection with the removal of colored matters from solution. He therefore studied the action of animal charcoal, deashed by boiling with dilute hydrochloric acid until silica only remained in the ash, and followed by complete washing to the absence of acid reaction, on a number of solutions, mostly of the inorganic type. In this paper he shows that such charcoal removes the blue color from ammoniacal copper solutions and that the copper cannot be removed from the charcoal by suhsequent extraction with strong ammonia. He points out that silver is adsorbed from a solution of silver nitrate and that crystals of metallic silver appear on the surface of the charcoal; that iodine is removed from a solution of iodine and potassium iodide and that the carbon can be dried a t a relatively high temperature without the appearance of iodine vapors. If, however, the iodinecharcoal mixture he heated strongly in a closed flask the iodine sublimes, hut later, on cooling, the charcoal readsorhs the iodine vapors. He found that the charcoal adsorbs chlorine from a solution of the gas in water hut that on the surface of the charcoal the chlorine is converted into hydrochloric acid. However, perhaps the most striking comment in this entire paper is his vision, in that early period of chemicalscience,as to the efied of adsorption on procedures in analytical chemistry. He states: The same property is possessed by other solid bodies, in a state of minute division, as when newly precipitated, although not in
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GRAHAM. TWMAS.A n m l ~of Philomphy, 12, R9-74 (1826).
' GRAHAM. TnoM~h,QtUt11 1. .% 2. 74-83 (1829) ' GRAHAM. THOMAS. Phd Trans. 1861. Dn. 1%-224.
so great a degree. And, in analytic researches, its interference must be guarded against, as it may contribute, in some cases, to increase the weight of precipitates.
Certainly no modern text in the field of analytical chemistry can state the facts more succinctly than this, and in manv texts descrihine analvtical nrocedure the possibility df adsorption is Gill w
