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274                       METALLURGY   OF   CAST   IRON.
mixtures for heavy guns should be made of iron possessing the greatest ductility, combined with strength, that can be obtained. Cold blast charcoal iron is the best for such castings and should be melted in an air furnace. General Rodman obtained from selected charcoal pig iron a very strong gun iron which had the following analysis: Silicon 1.34, sulphur .003, manganese i.oo, phosphorus .08, graphitic carbon 2.19, combined carbon .93. The casting is said to have been tough, with a fine granular fracture and a hard surface which machined easily; also that its elasticity was greatly due to its lowness in phosphorus and sulphur. Further analyses of gun mixtures are shown on pages 278 and 299.
flixtures for gun carriages, etc., as given by Titus Ulke, M. E., in the Iron Trade Review, December i, 1898, are found in the following four paragraphs and in Tables 51 to 54:
i. Castings weighing from 2 to 16 tons were made for the United States barbette and disappearing gun carriages by the Lorain Foundry Co., at Lorain, O., of the following mixtures (Table 51), melted in an air furnace, the charge weighing 17 tons:
TABLE   51.
Charcoal iron scrap. ..........................................................	3S to 4s per cent.
Cold blast charcoal iron (Vesuvius and Salisbury) ................. Warm blast charcoal iron (Rome and Pine Grove)	10 to 20       " 15 to 25        "
Coke iron (Napier, Dover, etc.)    ..           ..........                 .    ...	20 to ^s        "
	34,000 Ibs.
The average analysis of fifteen heats of the above mixture gave silicon .94, sulphur .05, manganese .31, phosphorus .44, graphitic carbon 2.40, combined carboned castings, be mixed wholly with cast iron scrap, no pig whateverod wheel by Mr. A. Whitney is also given in Table 46.sly the same depth.... Shop scrap     ......	15            x ro           x	1.50 i. So	22.50 iS.oo