2. Iron taken from a small casting, close-grained, and of a dull grey colour.
3. Iron cast horizontally, in bars of three-eighths of aninch square, eight inches long. 4. Iron cast vertically, same size as last. These castings were reduced equally on every side, to one quarter of an inch square ; thus, removing the hard external coat, usually surrounding metal castings. They were all subjected to a gauge ; the bars were then presumed to be tolerably uniform. The weights used were of the best kind that could be procured, and, as the experiment advanced, smaller weights were used.
As we have not space for detailing the particulars of each experiment, w a here add only the average results of them.
The experiments on cast iron, in cubes of one-eighth of an inch,—specific gravity 7.033, gave 1439 lbs. avoirdupois, as the average force required to crush them. On specimens of the same iron, one-eighth of an inch square, and one-fourth of an inch long, the average force required was 2116 lbs.
On specimens of the same thickness, but varying in length from one-half of an inch to one inch, the average result was 1758 lbs.
On cubes of a quarter of an inch of the some metal, gave 9773 lbs. as the average remit.
On one-fourth of an inch cubes, made from horizontal castings of specific gravity, 7.113 gave 10,114 lbs. as the average.
On one-fourth of an inch cubes, vertical castings,. specific gravity 7.074, the average was 11,136 lbs.
A prism, having a logarithmic curve for its limits, resemblinf a column, (it jyas one-fourth of an inch diameter, by one inch long,) broke with 6954 lbs.
The trials on prisms, of different lengths, one-fourth and one-half horizontal, gave 9414 lbs.
The same, vertical, gave 9982 lbs.
Horizontal castings, varying from three-eighths to six-eights of an inch x gave an average of 8738 lbs.
Vertical ditto, gave 85361bn.
But their hardness, according to Cavallo, follows this order, viz., Iron, Pla tinum, Copper, Silver, Gold, Tin, Lead.
Banks observes that iron is about four times as strong as oak, and six times as strong as deal Wood is from seven to twenty times weaker transversely than longitudinally. It becomes stronger both ways when dry.