Assaying

Abstract

ASSAYING was a term originally used to denote the estimation, by the agency of heat, of a particular metal in an ore, alloy, or other metallic compound. Since the publication of Agricola's work in 1556, numerous English translations of foreign treatises on the subject have been published. Amongst these may be mentioned the translations of the works of Erker (1629), Barba (1674), and Cramer (1774). Assaying by the dry way has changed so little that the methods and instruments described in these old books might still be successfully used. Since the introduction, however, of the rapid and accurate wet processes, improvements have quickly followed each other, and from a particular ore a larger yield is now obtained than was formerly the case, so that the dry methods are, with a few exceptions, rapidly falling into disuse, as in many cases they do not indicate with sufficient precision the amount of metal actually present in the ore. The modern English literature of assaying is confined to Mitchell's large treatise, and to the chapters given in Percy's works and in Phillips's “Elements of Metallurgy.” No small text-book, in which full cognizance is taken of wet processes, has hitherto been published, and a gap in our metallurgical literature has now been well filled by Mr. Hiorns's useful book, which is based on the course of instruction organized at the Royal School of Mines by Prof. W. C. Roberts-Austen, to whom the author, as an old pupil, dedicates his work. In all the Continental Schools of Mines, the instruction is conducted in a most unsatisfactory manner. Large classes rapidly pass through the various assaying processes, all the students working together with military precision at the Professor's word of command. In London, on the other hand, each student works independently, and is not permitted to pass from one metal to another until he can prove that he is able to constantly produce trustworthy results. As a student of the Royal School of Mines, Mr. Hiorns has thus had an excellent training for the task he has undertaken. Besides this, as Principal of the School of Metallurgy at the Birmingham and Midland. Institute, he has had ample opportunity of ascertaining the wants of the average student. Practical Metallurgy and Assaying: a Text-book for the use of Teachers, Students, and Assayers. By Arthur H. Hiorns. Pp. 471, with 91 Illustrations, Appendix, and Index. (London: Macmillan and Co., 1888.)