114 METALLURGY OF CAST IRON. The first edition of this work recommended the adoption of these casting machines, and all that was said in their favor has been verified by practice., The economy and advantage to be obtained by using chilled or sandless pig metal in foundries, steel works, etc., maybe stated as follows: First, being a harder iron by reason of its chill or density, which holds the carbon more in a combined form, as well as having pigs free of sand (silica), less time and fuel will be required to melt it. Second, the pig being sandless there will be less fluxing needed and less slag to take care of in large heats; this will also give a cleaner iron to pour moulds, whether for small or large heats. Third, being a chilled iron or more dense it will give a softer re-melt than if the furnace iron had been cast in sand moulds. This is a discovery made by the author, the details of which are found on page 338. Fourth, by pouring furnace metal from ladles, better mixed metal will be obtained in a car or cast of pig iron than by casting pigs in sand moulds. The value of this will be better understood by reading Chapter XVIII. Some founders, understanding by experience the value of having the iron charged into cupolas as free of sand, scale, or dirt as possible, go to the labor of tumbling all their gates, etc. Could such founders also secure their pig iron free of sand, they could derive still greater benefit by having clean iron to re-melt and pour into their castings. What sandless pig the author has used proved much preferable to sand pigs in several ways. This experience is endorsed by others, as can be seen by the following extracts from a few letters which he obtained during 1899 by courtesy of Mr. Edgar S. Cook, president of the Warwick Iron Co. of Pottstown, Pa. is often surprising how rapidly, as about 75 per cent of the heat generated from the solid fuel is utilized. This is attained where one ton of coke will produce one ton of iron; and Sir........................ 2,720 "