The Chemical Philosophy of Thomas Sterry Hunt EDWARD R . ATKINSON University o f New Hampshire, Durham, New Hampshire
HE CHEMISTRY student of today is often un- versity. He then returned to the States and sucaware of the fact that many of the chemical theories ceeded William Barton Rogers as professor of geology which now enjoy universal acceptance have achieved a t the Massachusetts Institute of Technology. He this state only after a prolonged period. He may be later resigned this position to enter consulting work. surprised to learn that as recently as 1920 there were Hunt was a Fellow of the Royal Society (1859), a mempopular texts in general chemistry which not only ber of the National Academy of Sciences (1873), presifailed to use the ionization theory of Arrhenius but were dent of the American Association for the Advanceeven antagonistic toward this theory. At a time when ment of Science (18il), and twice served as president the atomic-molecular hypothesis was over one hundred of the American Chemical Society (1879, 1888). His years old it was not acceptable to many noted chemists. lifelong work with complex mineral substances was well known to the geolo~ i l h e l mOstwald gists of America refused to accept a n d of E u r o p e . it because he felt Organic chemists t h a t chemistry remember him as should be stripped the first American of as much hypochemist to deiine thetical material their science as the as possible; obchemistry of the viously he did not compounds of caragree with Helmbon, and as the holtz w h e n t h e originator in 1854 l a t t e r remarked, of a Type Theory "There is nothing w h i c h i n some more useful than a respects anticigood theory." In p a t e d t h a t of this country a noted Williamson and chemist, Thomas Gerhardt.' Sterry Hunt, also Hunt's chemical refused to accept philosophy was dethe hypothesis. In veloped during the contrast to Ostperiod 1850-1885 wald, Hunt had no and was presented dislike for theory in a number of in general, but he papers including felt that theatomicthat entitled "A molecular hypothecentury's progress sis was inferior to in chemical theory" other hypotheses which he read which p e r t a i n e d a t t h e Priestley to t h e chemiCentennial a t c a l n a t u r e of Northumberland matter. in 1874. T h e s e Thomas Sterry papers were Hunt was born a t summarized Norwich, Connecticut, in 1826. He was a student of the elder Silliman and published in book form in 1887. A second a t Yale and then sewed as chemist and mineralogist and revised edition of this work appeared a year with the. Geological Survey of Canada until 1872. For additional biographical data see L. C. Newel1 in "DicUniver- tionary During this period he was a founder of American biography/ Scribnerrs,New York, 1932, sity and taught chemistry there and at McGill Uni- VOI. 9,p. 393. 244
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later and was translated into French and R u s ~ i a n . ~weight and density was simply a measure of molecular Repelled by contradictions of the atomic hypothesis, volume. The equivalent weights of gaseous substances were Hunt chose to base his chemical philosophy on the principle of continuity of mass, a concept which de- easily derived from their vapor densities by the use of scends from Pythagoras, Plato, Aristotle, and Kant. the "Law of Volumes." hydrogen gas being used as a Chemical combination was not the union of atoms ~ t a n d a r d . ~Some substances such as sulfur and iodine and molecules but was essentially an interpenetraiia began to polymerize even in the gaseous $ate, but of the masses involved so that the uniting bodies occu- water did not show this peculiarity and so was chosen pied the same space. The concept of hard indestruct- as a secondary standard. The density of steam was ible particles (atoms) which had been so successfully determined a t standard conditions and the density of applied to chemistry one hundred years before by liquid water a t the boiling point (Kopp). From these William Higgins and by Dalton was beyond the limits measurements it appeared that 1192 volumes of steam condensed to one volume of water. The equivalent of sound philosophy. Chemical change was either combination or division. weight of water was therefore 1192 X 17.96 = 21,408 If a new species resulted the term metagenesis was used; (approx.). Hunt then assumed that the Law of if only a single species was involved the term meta- Volumes held for the liquid and solid states and promorphosis or polymerization was used. The new species ceeded to calculate the equivalent weight of any species formed in metagenesis gave no clue as to the composi- by multiplying its specific gravity by 21,408. Such a tion of the original species. For example, the mineral procedure led to difficulties when dealing with a species calcite did not consist of calcium, carbon, oxygen, or of such as calcium carbonate which existed in several calcium oxide and carbon dioxide just because these crystalline modifications, each with its own peculiar materials were formed when the calcite decomposed. specific gravity. Hunt avoided these difficulties by Hunt did accept the existence of elements, but he did stating that each crystalline form was a distinct not believe in their discrete pre-existence within com- chemical species, Tiering from the others in degree of pound substances. All elements were polymers of an polymerization. This diierence would of course exideal element (following Prout) and this ideal element plain the variations in hardness and in reactivity was responsible for the presence of certain spectral toward acids which these minerals showed. Hunt insisted on a clear distinction between chemlines found in the light of the sun and nebulae. As these heavenly bodies cooled, the ideal element poly- istry and dynamics (elasticity, temperatme, electricity, merized, and because polymerization was an exo- movements of gases). He believed that both were thermic reaction, the liberated heat caused the tem- manifestations of a universal motivating force, but that perature of the star to rise again; this was offered as Faraday and Helmholtz had no right to state that chemistry was concerned with molecular motion or an explanation for variable stars. The formation of a solution was a good example of with electrical forces. The atomic-molecular hypotha chemical process, for in the last analysis all chemical esis was admittedly useful in the field of dynamics. union was the formation of a mutual solution by the Chemists, however, were concerned not with the comreacting species. Other typical chemical phenomena ~ositionof a species as such-their true interest lay in were condensation (polymerization) and evaporation the relation of one species to another. Lookmg back over fifty years we find much in Hunt's (depolymerization). In these cases there should be a strictly quantitative relation between the equivalent chemical philosophy that is good, much that is stimuweight and the specific gravity of liquids and solidss lating. But the striking developments in physics and The more dense a liquid, the more complete the poly- chemistry since his death in 1892 were made possible merization which occurred when the liquid was formed. by the firm basis of the atomic-molecular hypothesis. The atomists held that this relation between equivalent The corpuscular concept has been extended to energy itself. Today, after one hundred and fifty years of increasing usefulness, the atomic-molecular theory has gained universal acceptance. -
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HUNT."A new hasis for chemistrv." . S. E. Cassino. Boston.
1888, 2nd'ed.
In the discussion which follows the term molecular weight may he substituted for Hunt's equivalent weight. Hunt never used the former for he did not believe that molecules existed. a
4 This "Law of Volumes" is simply a combination of GayLussac's Law and the then emerging hypothesis of Avogadro. Note that these same factors served as a basis for the determination of molecular weight by the atomists Hunt was aware of this.
