The Alloys of Copper and Zinc

ON account of their great industrial importance, the alloys of copper and zinc have at various times been studied by many observers. Mallet, Matthiessen, Riche, Thurston, and a host of others have made contributions of varying importance to the literature of the subject; but so difficult is it to eliminate the accidental differences in the physical conditions that Prof. Thurston announced, as late as the year 1893, that the curves representing the variations in the properties of brasses were so irregular that the effects of composition only (irrespective of other conditions) must remain unknown until further researches should be made. To the task thus indicated M. G. Charpy has addressed himself, and has succeeded in notably advancing the knowledge on the subject.1 He did not confine himself to the mechanical properties, but has also made a careful investigation of the micrographic properties of a number of alloys, a branch of the subject which had already been attacked by Guillemin and by Behrens in 1894.