University and Educational Intelligence

Abstract

OXFORD.—The 197th meeting or the University Junior Scientific Club was held in the large lecture-room of thet museum on Wednesday, February 15, the President in the chair. There were present ninety members and twenty visitors. Prof. Odling delivered a lecture on chemical views in controversy about the year 1850. The following is an abstract of the lecture: To put back the clock is always a very difficult task, and to understand exactly the views of chemists of fifty years ago is extremely hard, as one must forget for the time being all that has been discovered since. In chemistry, as in most other sciences, the tendency is to look forward and not backward; but it must not be forgotten that the future will be but a development of the present, as the present has been a development of the past. The evolution of chemistry has taken place along one continuous line, broken here and there by great fundamental discoveries, which have been rather apt at first to warp the line of development, and to make it a little one-sided. Thus the striking aptness of Dalton's atomic theory to explain the laws of chemical combination, which he had formulated, and the tables of proportional numbers deduced from them, attracted the attention of chemists to the determination of atomic weights. The importance of molecular weights, or as Prof. Odling preferred to call them unit weights, of compounds was not fully recognised till some half-century later, although Avogadro had pointed the way in his hypothesis put forward in 1811. In the forties Laurent and Gerhardt began to investigate unit weights, and laid the foundation of our present system. In this country Williamson and Brodie were the chief workers at the subject, and Prof. Odling described himself as their junior colleague to whose share much of the fighting fell. They had before them the problem of determining correct atomic weights for the elements, a problem which could only be solved after correct determinations of the unit weights of their compounds; and they considered that physical evidence as to unit weights must be confirmed by the chemical behaviour of substances. Hence the importance of Williamson's theory of etherification; for by showing that ether was not merely the oxide of a hydrocarbon radical, but that it was a combination of two hydrocarbon radicals with oxygen, he was able to deduce the unit weights of alcohol, ether, and other compounds compared with that of water, and to show that the carbon always combines in multiples of twelve, and oxygen in multiples of sixteen, and so these numbers must represent the real atomic weights. It was some years, however, before these new atomic weights, based on a true conception of unit weights, were generally accepted. The first text-book in which sixteen was used throughout as the atomic weight of oxygen being Prof. Odling's “Manual of Chemistry,” published in 1861. Subsequently Newlands, from the revised atomic weights, suggested the periodic system of the elements, which was developed by Prof. Odling and Lothar Meyer, and completed by Mendeléeff. The chief work of chemists during the last quarter of a century might be briefly described as the investigation of the internal structure of the chemical molecule, and this, being dependent on an accurate knowledge of unit and atomic weights, is but the natural development of the most important work of the fifties-the correct determination of unit weights.