This process produced ingots absolutely solid and free from defect, which had been proved impossible by the mere use of pressure. The expense of all these methods, and the inconven ience of applying them to the open ingot molds universally used for casting steel ingots, re sulted in the invention by Mr. J. B. D'A. Poulton, of Jersey City, N. J., of an apparatus in which ingot molds made without bottom, but in other respects like the common ingot molds, are superposed, one upon another, and successively filled, the shrinkage in each ingot being fed by the fluid metal in that above it, and the resulting product being a series of absolutely sound ingots connected by cold-shut joints. An ingot made by this process, and split open, has been shown to be perfectly sound. By interposing an asbestos washer with a small aper ture between the successive mold sections, the resulting product was necked at intervals, so that the ingot bar could be readily broken at such points. Boulton's apparatus has been in commercial operation at the 'West Bergen Steel Works of Messrs. Spaulding & Jennings, since December, 1887, and one ingot per minute is cast in it regularly when the heat is ready. The ingots cast are nearly 4 in. square, and are absolutely sound ; but the machine is equally adapted to cast larger ingots by making the holder and the ingot molds of suitable dimen sions. One man suffices to operate the levers of the hydraulic apparatus, and the ordinary operators are employed to pour the metal.
Mr. William D. Hinsdale obtained a United States patent, dated January 0,1891, No. 444, 381, for a process of forming ingots, which he states consists, essentially, in chilling the sur face of the ingot which is last cast in the mold, and which is therefore the hottest, and in reversing the ingot after such surface is sufficiently chilled to exclude the atmosphere from the fluid interior of the ingot.
In this invention the retention of the fluid metal within the chilled shell is absolutely es sential, whereas in earlier methods the discharge of the fluid metal is the ultimate object, and the chilling of the top end of the casting before reversing the ingot is carefully avoided. One of the claims of the patent is a:: follows : The process of forming ingots, which consists, first, in inserting a cup of heated material in the bottom of the mold ; secondly, filling the mold ; thirdly, excluding the atmosphere from the mouth of the mold ; and, fourthly, reversing the mold, as and for the purpose set forth.
Steel Castings.—Fig. 9 is taken from a photograph of a box-slide casting made by the Nedvale Steel Co., of Nicetown, Pa., for the 12-in. turret mount for the United States tur ret ship Puritan, in October, 1891. The government specifications under which this casting was made are as follow : Tensile strength, 05,600 lbs. per sq. in.; elastic limit, 25,0110 lbs. per sq. in.; extension, 15 per cent.; contraction, 25 per cent. The result of the tests made from this casting showed that the steel possessed the following physical characteristics : Tensile strength, 65,174 lbs. per sq. in.; elastic limit, 31,058 lbs. per sq. in.: extension, 25.10 per cent.; contraction, per cent. The weight of the casting was 15,547 lbs.
In addition to the tests above given on the sheet enclosed, the casting was put to a bal listic test, to determine the ductility of the metal. This test is made by subjecting the pieces to the fire of rapid-tiring guns at short range, and the castings are accepted if it is shown by this test that they can be bent or perforated by projectiles fired from these guns without breaking. Ordinary steel castings, if put to this lest, are apt to fly to pieces at the first discharge. thus making the gun sought to be shielded useless, and probably causing much loss of life. The combination of high elastic limit, extension, and contraction in the casting illustrated, indicates that it would withstand an immense amount of'battering with out going to pieces, and that it is particularly well suited for the purpose intended. What is chiefly remarkable about this casting is, that while the tensile strength developed is but 174 lbs. above the government requirements. the manufacturers succeeded in increasing the elastic limit by per cent., the extension by 07 per cent., and the contraction by 40 per cent. beyond the requirements. That this was not an accidental performance was shown by the fact that subsequent castings from the same pattern have shown in the average fully as good results.
Stem, Cation Picking : see harvester, Cotton.
Step: see Water-wheels.