A group of 4 items relating to Alexander Crum Brown and Augustus Harcourt:
1. BROWN, ALEXANDER CRUM. 1838-1922.
"On the Classification of Chemical Substances, By Means of Generic Radicals." Edinburgh: 1866. Offprint. INSCRIBED BY CRUM to "The Royal Medical Society, From the Author." Lacking wrappers, society ink stamp on title, toning.
2. Engraved portrait of Brown by William Hole. [Edinburgh: 1884.] Sheet size 8 3/4 x 12 inches.
3. HARCOURT, AUGUSTUS GEORGE VERNON. 1834-1919. "On the Rate at which Chemical Actions Take Place." Offprint (removed from a bound volume). London: Royal Institution of Great Britain, 1867. Light toning.
4. ---. On the Observation of the Course of Chemical Change. OFFPRINT FROM: Philosophical Transactions, 1867. Disbound (removed from a bound volume). Folding plates.
Alexander Crum Brown received his M.D. from Edinburgh University with a thesis on the theory of chemical combination. "In his thesis Crum Brown discussed chemical structure and the application of mathematics to chemistry. The first attempts had just been made to represent the structure of compounds by various types of graphical formulas. Crum Brown was dissatisfied with the unwieldy diagrams invented by Kekule and proposed a more convenient scheme. He represented constituent atoms by circles drawn around the usual letter symbols, with a number of lines proceeding from them according to valences. In 1865 he invented the symbol, which is still in use, of two parallel lines for a double bond" (DSB 2:514-515). "Essentially [Brown's] was the system of notation later employed universally. For clarifying atomic relationships within a molecule, according to the new valency theories of Edward Frankland and Kekule, this simple device was of untold value and greatly facilitated the emergence of the theory of structure upon which later chemistry was predicated" (ODNB 8:5-6). The rare inscribed offprint here includes the symbols Brown invented and explains their meaning.
"Augustus George Vernon Harcourt ... is considered to be the first scientist who made a significant contribution in the field of chemical kinetics" (P. Ptacek, T. Opravil and F. Soukal. "A Brief Introduction to the History of Chemical Kinetics. 2018). "Harcourt, in 1866, aided by his mathematician colleague William Esson, discovered independently of Guldberg and Waage the law of mass action in its simplest form: 'The velocity of chemical change is directly proportional to the quantity of substance undergoing change'" (DSB VI:109-110). "Harcourt and his kinetic work have been treated very comprehensively by Christine King and John Shorter, and there is no doubt that these investigations played a very important role in the development of the field of chemical kinetics" (K.J. Laidler, "Chemical Kinetics and the Origins of Physical Chemistry," in Archive for History of Exact Sciences, 1985 32: p 47).