METALLURGY OF CAST IRON.
samples are given in Table 26 and illustrated in Figs. 40, 41, and 42.
TABLE 26.—CHEMICAL ANALYSES OF PIG SPECIMENS.
Fig. Silicon. Sulphur. Manganese. Phosphorus.
40 4* 42 .98 1.82 3-30 .015 .018 .017 •30 •35 •34 .092
The author has numbered the above irons from the appearance of their fracture and not from the chemical analysis, as an iron 3.30 (Fig. 42) in silicon with sulphur as shown would prove a good No. i iron when re-melted, but the fracture would assert it to make No. 9 or hard iron. Then again, in judging by fracture Fig.
41 would make a very hard iron, while Fig. 40 would make a very soft casting, when in truth the reverse results would be obtained by both as shown by the analyses. It will be seen by the Table 26 that the chemical analyses of these three samples are practically all the same excepting in the silicon contents. The author could present any number of specimens which would be as deceptive to the eye in judging their grade by fractures, etc., but what is given in this chapter should be sufficient to illustrate that we cannot be always correctly guided by the appearance of the fracture (or hardness of pig iron, as treated in the next chapter) to define the grade of iron when re-melted or poured in castings. The pig samples seen in Figs. 40, 41 and
42 are numbered after the method advanced in table 22, page 152.e made from the pig, sample A, were also much harder than those made from sample B. In measuring the depth of the chill, pieces were broken off one end of the test bars as seen at P, Fig. 37.ith chemical analysis, or the effect of one metalloid upon another, that they are in error, the writer melted down about one hundred pounds of each of the grades A and B in his twin-shaft cupola, seenng the advance of the new, see page 179.n is simply an average of the whole, generally taken from the two ends andith the uncertainty of furnace workings when in urgent need of ten hundred jon of iron; and Sir........................ 2,720 "