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Charles Thomas Heycock (c1858-1931) of the University of Cambridge
1931 Obituary 
CHARLES THOMAS HEYCOCK, M.A., F.R.S., an Original Member of the Institute, died on June 4, 1931, at the age of seventy-three. By his death the Institute of Metals has lost one of its most distinguished scientific members.
Owing to his preoccupation with many activities in Cambridge, Mr. Heycock rarely attended meetings of the Institute, but the high value of his scientific work in metallurgy and the inspiration which he gave to a group of young metallurgical investigators have been much appreciated and will be very much missed. This is scarcely the place to dwell upon the many excellent and remarkable qualities of Heycock as a man and as an active and important member of his University. All those who, like the writer, had the privilege of coming into close personal contact with him in Cambridge have realized the breadth and importance of his activities there. Their scope may be estimated by the fact that he was not only at one time Deputy Lieutenant of the County, but also rose to the rank of Honorary Colonel of Volunteers.
His greatest service, apart from his scientific work, however, probably lay in the effect of his remarkable personality on the many generations of young men with whom he came into contact. In an entirely different direction, Heycock's personality, added to his scientific attainments, made an impression upon an important Livery Company of the City of London (the Goldsmiths' Company) which led to far-reaching developments, including the foundation of a Readership in Metallurgy at Cambridge which now promises to become a full Professorship.
On the other hand, Heycock attained a distinction, very rare if not unique in a Cambridge Don, of becoming Prime Warden of a City Company. Heycock's metallurgical work, in which he was closely associated with the late H. F. Neville, was of a fundamental and pioneering character. He approached the problem of the constitution of alloys definitely from the point of view of the chemist, and he was, indeed, a scientific chemist investigating the chemistry of alloys rather than a metallurgist.
Some of his earlier work related to the molecular depression of the freezing point of liquids by solutes as exemplified in the solutions of one metal in another. This led to the determination, in the first instance, of what we now term the liquidus curves of several alloy systems.
Later, the study of the equilibria of alloy systems in the solid state and during solidification exercised its fascination upon Heycock and Neville, and they were led to embark on the study of the complex system of alloys formed by copper and tin. Here, they began to avail themselves of the methods of microscopic examination, and for the first time used, in a metallographic research, the device of annealing or slowly cooling small specimens at or to definite temperatures, and then chilling them rapidly in order to retain the microstructure which they had reached at that temperature. This highly fruitful method allowed them to determine the equilibrium diagram of the copper-tin alloys with a high degree of accuracy at a time when other investigators, relying almost exclusively on cooling curves taken with rather crude apparatus, were producing numerous diagrams full of inaccuracies.
It was not until many years later that the annealing and quenching methods devised by Heycock and Neville came to be widely used and recognized. The equilibrium diagram of the copper-tin system put forward by them has been subjected to a certain number of minor corrections, but still stands, in its broad outlines, as the first of the more complicated diagrams to be established on a sound scientific basis.
The death of Heycock, therefore, removes from among us not only a man whom many had the privilege of regarding as a valued personal friend and teacher, but also a pioneer investigator whose name ranks high among the founders of modern scientific metallurgy. WALTER ROSENHAIN.