Metallurgy Of Cast Iron

METALLURGY OF CAST IRON.
bar. He mentions this fact for the reason that in the discussion above cited, one member of the American Society took the position that the specific tests on page 379 were inadmissible- proofs to establish any principle, owing to the bottom end of the gun which was cast down being of a more massive nature than the tipper end, and hence there was good reason to expect metal to be less dense in the bottom than in the npper end of the gun. The following test of the parallel gate which the author conducted shows the fallacy of the idea that the lower end of vertical-poured castings must be of a greater specific gravity than the upper end. In the experiment which the author conducted at his own foundry, he took a '' gate '' 6*4 feet long and 3 inches in diameter, which had been used for pouring an iron ingot mould casting, and took a test-piece 6 inches from the top, and another 5 feet from the top. The gate was practically parallel, so that, in turning these specimens in the lathe, the same amount of surface was carefully removed from each. The specimens were machined of exact size, and were then delivered to the laboratory of the Case School of Applied Science, of Cleveland, O., to be weighed. The determinations (Table 83) reported by Prof. C. H. Benjamin were as follows:
TABLE 83.
Weight of top end of gate in vacuum......................1169.468 grammes.
Weight of bottom end of gate in vacuum.................1167.239 "
Volume of top end of gate......................................... 165.722 cubic centimetres.
Volume of bottom end of gate................................... 165.768 " "
1169.468
Density of top end of gate......................................... —----------— 7.0568.
165.722 1167.239
Density of bottom end of gate.................................. —----------=«* 7.0414.
165-768 Difference=o.oi54 only. The plug from the upper end is the denser.20 19.10 Ferrochrom.