50 and 100 Years Ago in The Journal of Physical Chemistry – 2025 Edition

Abstract

In this series of editorials we look back at the work published in the Journal of Physical Chemistry 50 and 100 years ago. In 1925, The Journal of Physical Chemistry published 153 articles, a 40% increase from the previous year and continuing the trend of journal growth in the 1920s. A large number of the papers dealt with the properties of colloids and emulsions, which was an important topic at the time and a major focus of the Journal’s editor-in-chief. The most prolific authors were N. R. Dhar from the University of Allahabad, India, and W. A. Patrick from Johns Hopkins University with eight papers each. Patrick pioneered a method to quickly and cheaply produce silica gel, which has a variety of uses, an important example being as the active agent in gas masks in World War I. His papers and correspondence have been archived by Johns Hopkins University. All of Patrick’s papers published The Journal of Physical Chemistry in 1925 were studies of absorption of different species onto silica gel, except for a study of boiling points and conductivity of soap in alcohol solutions. (1) The soap study showed, not too surprisingly, that sodium oleate is dissociated in alcohol solutions at the boiling point. Dhar published on a wide range of topics including the viscosity of colloid solutions, (2) studies of corrosion of metals by nitric acid, (3) how the color of colloidal solutions changes with ion adsorption, (4) and photosynthesis in tropical light compared to artificial UV light. (5) Dhar was an extremely prolific scientist, and was an early leader of physical chemistry in India. The most cited papers in 1925 were studies of the performance of different types of adhesives by McBain and Hopkins (6) and how thin films affect water evaporation by E. K. Rideal (who later achieved fame for his work on surface catalysis). (7) A diagram of the apparatus used by McBain and Hopkins to measure the strength of adhesives is shown in Figure 1. (6) This paper was cited 14 times in 2024! Also in 1925 Kharasch and Sher presented a 33-page “preliminary communication” on determining the heat of combustion by counting the number of valence electrons─see Figure 1. (8) In their view of bonding, atoms have a series of orbits and two atoms can hold a pair of electrons at the points where the orbits intersect. Which orbit is used depends on the affinity of the atom for electrons. Although this is not the modern view, the differences between the calculated and measured heats of combustion were generally <1%, which is outstanding. Also in 1925 Barker published a similar set of calculations based on Lewis structures; (9) however, the predicted combustion energies were less accurate. The Journal also published two papers on the stabilization of gold colloids (“Zsigmondy’s gold sols”) by surface active agents (10,11) and four papers on the properties of phosgene (dielectric constant, conductivity and solution density) by Germann and co-workers. (12−15) The work on phosgene was “carried out in collaboration with the Chemical Warfare Service, with phosgene supplied from Edgewood Arsenal”. It is important to note that the use of chemical warfare agents in battle was banned by 1925. The Journal also published a much safer paper on how the rate of growth of Lemna Major (duckweed) is affected by the intensity and duration of light. (16) This would now be out of scope for the Journal, although the authors applied a fairly rigorous kinetic analysis to the data! Figure 1. Left: Experimental apparatus for measuring shear strength of different types of adhesives. (6) Reprinted with permission from ref (6). Copyright 1925 American Chemical Society. Right: Scheme for bonding between atoms proposed by Kharasch and Sher. Electrons are held at the intersection between orbits, and which orbits are used depends on the identity of the atoms. (8) Reprinted with permission from ref (8). Copyright 1925 American Chemical Society. Finally, 13 papers were published in Issue 10 of The Journal of Physical Chemistry in 1925 from the “Plasticity Symposium”, which was held at Lafayette College in October 1924. This “Special Issue” included an Introduction to the symposium (like the Special Issues published today) (17) and mostly described studies of the plasticity of different compounds, such as dental materials. (18,19) Not all the authors for the Special Issue had new work for publication, one author wrote a short article complaining about the use of microscopes in research into plastic materials, and how many people in the field are confused. (20) The Journal of Physical Chemistry also saw an increase in the number of published papers in 1975: a more modest 7% compared to 1925 but thankfully reversing a trend of declining publications. The most highly cited paper (by over a factor of 5!) was a Review Article by Scheraga and co-workers that compiled the parameters (geometric parameters, partial atomic charges, nonbonded interaction energies, hydrogen bond energies, etc.) for the interatomic potentials of naturally occurring amino acids. (21) Review articles were relatively rare in the Journal in the 1970s; only four were published between 1970 and 1980. Scheraga’s paper is still cited today, most recently in an Editorial on the importance of simulation software and force fields in computational biophysics. (22) The most prolific author in 1975 was Ellen Hayon who published seven papers (one more than Scheraga). Hayon published almost 50 articles in The Journal of Physical Chemistry over her career, all on pulse radiolysis/flash photolysis studies of transient species and mostly while at the U.S. Army Natick Laboratories. In 1975 Hayon’s most cited paper in The Journal of Physical Chemistry was a study of the redox potentials of the O₂^– and HO₂ radicals, which were produced by pulse radiolysis. (23) Like in previous years, electron spin resonance (ESR) and pulse radiolysis/flash photolysis studies were very popular in The Journal of Physical Chemistry (JPC), accounting for a significant number of the highly cited papers. Figure 2 shows a beautiful ESR spectrum of a radical cation produced by pulse radiolysis (high energy electrons in N₂O saturated solutions create OH radicals which react with organic species to produce radicals). (24) The second most popular topic among the highly cited papers was micelles and polyelectrolytes. In particular, Aniansson and Wall published a “correction and improvement” of their 1974 JPC paper on “Kinetics of Step-Wise Micelle Association” that has been cited almost 300 times. (25) Figure 2. ESR spectrum of 1,2-dimethoxybenzene radical cation reprinted with permission from ref (24). Copyright 1975 American Chemical Society. In 1975 Issue 26 of The Journal of Physical Chemistry (the last of the year) was a Special Issue on electrons in liquids that originated from the “Colloque Weyl IV” conference (Weyl being the discoverer of solvated electrons in ammonia solutions in the 1860s), which was held at Michigan State University in the summer of 1975. The Special Issue contained 58 papers, and remarkably 86% of the researchers who presented at the conference ended up publishing a paper in the Special Issue. Interestingly, most of the papers included a transcript of the discussion of the presentation at the end of the paper, and the issue was published just five months after the conference was held. The Colloque Weyl continued up to version 7, which was held in 1991. The papers presented as part of Colloque Weyl IV included ab initio studies of solvated electrons, (26,27) picosecond time-resolved measurements of the dynamics of electrons in liquids, (28,29) and analysis of metal–insulator transitions in metal-ammonia solutions by Jortner (30) and Mott. (31) Many of the papers in this Special Issue ended up as the most highly cited papers in 1975. This editorial is jointly published in The Journal of Physical Chemistry A/B/C. This article references 31 other publications. This article has not yet been cited by other publications.