from No. 4 were tested, when the maximum strength was reached.  No. 4 pig iron was in fracture a pale gray, bordering on mottled.  Several points regarding foundry operations in the production of chilled castings were raised for discussion.  They embraced the depth of chill to be imparted to chilled rolls and railway wheels, and in the case of traction wheels, the width of chill in the tread; preparation of the chills—­by coating with various carbonaceous matters, lime, beer grounds, or, occasionally, some mysterious compost—­and moulds, selection and mixture of pig irons, methods and plant for melting, suitable heat for pouring, prevention of honeycombing, ferrostatic pressure of head, etc.  Melting for rolls being mostly conducted in reverberatories, the variations in the condition of the furnace atmosphere, altering from reducing to oxidizing, and vice versa, in cases of bad stoking and different fuels, were referred to as occasionally affecting results.  Siemens’ method of melting by radiant heat was mentioned for discussion.  For promoting the success of a chilled roll in its work, lathing or turning it to perfect circularity in the necks first, and then turning the body while the necks bear in steady brasses, are matters of the utmost importance.

The author next referred to the great excellence for chilling purposes possessed by some American pig irons, and to the fact that iron of a given carbon content derived from some ores and fluxes differed much in chilling properties from iron holding a similar proportion of carbon—­free and combined—­derived from other ores and materials.  Those irons are best which develop the hardest possible chill most uniformly to the desired depth without producing a too abrupt line of division between the hard white skin and the softer gray body.  A medium shading off both ways is wanted here, as in all things.  The impossibility of securing a uniform quality and chemical composition in any number grade of any brand of pig iron over a lengthened period was adverted to.  Consequent from this a too resolute faith in any particular make of pig iron is likely to be at times ill-requited.  Occasional physical tests, accompanied with chemical analysis of irons used for chilling, were advocated; and the author was of opinion it would be well whenever a chilled casting had enjoyed a good reputation for standing up to its work, that when it was retired from work some portions of it should be chemically analyzed so as to obtain clews to compositions of excellence.  Some of the physical characteristics of chilled iron, as well as the surprising locomotive properties of carbon present in heated iron, were noticed.