B. — CHEMISTRY, 51 



to show the pitfalls which have been avoided in the theoretical inter- 

 pretation of the obsei-ved facts, and to sketch verj- briefly the present 

 position of our knowledge. 



The production of metals and their alloys undoubtedly constitutes 

 the oldest of those chemical arts which ultimately expanded into the 

 modern science of chemistry, with all its ovei-whelming mass of experi- 

 mental detail and its intricate interweaving of theoretical interpretation 

 of the obsei'ved facts. Tubal-Cain lived duiing the lifetime of our 

 common ai:icestor, and was ' an instructor of every artificer in brass 

 and ii-on ' ; and although it may be doubted whether the philologists 

 have yet satisfactorily determined whether Tubal-Cain was really 

 acquainted with the manufacture of such a complex metallic alloy as 

 brass, it is certain that chemical science had its beginnings in the 

 reduction of metals from their ores and in the preparation of useful 

 alloys from those metals. In fact, metallic alloys, or mixtures of 

 metals, have been used by mankind for the manufacture of implements 

 of war and of agriculture, of coinage, statuary, cooking vessels, and the 

 like from the very earliest times. 



In the course of past ages an immense amount of practical informa- 

 tion has been accumulated concerning methods of reducing metals, or 

 mixtures of metals, from their ores, and by subsequent treatment, 

 usually by heating and cooling, of adapting the resulting metallic 

 product to the purpose for which it was required. Until quite recent 

 times, however, the whole of this knowledge was entirely empirical 

 in character, because it had no foundation in general theoretical prin- 

 ciples ; it was collected in haphazard fashion in accordance with that 

 method of trial and error which led our forerunners surely, but with 

 excessive expenditure of time and effort, to valuable results. 



To-day I purpose dealing chiefly with the non-ferrous alloys, not 

 because any essential difference in type exists between the feiTous and 

 non-ferrous alloys, but merely because the whole field presented by the 

 chemistiy of the metals and their alloys is too vast to be covered in 

 any reasonable length of time. 



The earliest recorded scientific investigations on alloys were made 

 in 1722 by Reaumur, who employed the microscope to exa.mine the 

 fractured surfaces of white and grey cast iron and steel. 



In 1808 Widmanstatten cut sections from meteorites, which he 

 polished and etched. 



The founder, howe\Ter, of modern metallography is undoubtedly 

 H. C. Sorby, of Sheffield. Sorby's early petrographic work on the 

 examination of thin sections of rock under the microscope led him to 

 a study of meteorites and of iron and steel, and in a paper read before 

 the British Association in 1864 he describes briefly (I quote his own 

 words) how sections ' of iron and steel may be prepared for the 

 microscope so as to exhibit their structure to a perfection that leaves 

 little to be desired. They show various mixtures of iron, and two 

 or three well-defined compounds of iron and carbon, graphite, and 

 slag; these constituents being present in different proportions atnd 

 arranged in various manners, give rise to a large number of varieties 

 of iron and steel, differing by well-marked and very striking peculiarities 



