256 
GEOLOGY OF THE SECOND DISTRICT. 
Extract from a Report, hy Prof. W. R. Johnson, of experiments on the iron manufactured 
at the village of McIntyre, Essex county, New-York. 
To ascertain the toughness and ductility of this iron, when cold, I caused the bar to be bent 
at a temperature of 50°, at a part where the breadth was 1 • 295 inches, and the thickness 
O’ 59 inch. This bend was made flatwise, and continued until 
the corresponding faces on the inside, about one inch from the 
middle of the inner curve, were O’4 of an inch apart, and the 
widest part of the opening only 0’45 of an inch. The altera¬ 
tion in the form of the bar appeared to be limited to this por¬ 
tion. On measuring along the interior and exterior edges of 
this curve, the former was found to be 2 ’ 15, and the latter 
3’ 8 inches ; manifesting a difiercnce in the length of the inner 
and outer fibres, of 1’65 inches in a length of about 2|, the 
original extent of the bent portion (see fig. 1). By this trial, 
the whole form of the cross section of a bar is changed, and 
instead of straight lines, exhibits only curves. In the present 
case, the parallelogram fig. 2 was converted into the form of fig. 3, the largest curve being on 
the inside of the bend. 
Fig. 3. 
This change of figure and displacement of parts were borne without exhibiting any signs of 
rupture, until the curvature above stated had been attained, when a few cracks began to appear 
on the exterior part of the curve. 
The next test to which this iron was subjected, was to heat a portion of the bar to redness, 
quench it in cold water, and then bend the same portion cold, in the manner already described. 
No difference of result was obtained, except a greater facility in producing it. A few slight 
surface cracks were seen near the close of the operation. 
A third trial of a similar kind, on a bar annealed and cooled in dry ashes, resulted like the 
preceding, but exhibited rather more cracks on the exterior surface of the bend than either of 
the foregoing. 
Another trial of the toughness of this iron, when cold, was made by drawing out a bar 0’7 
of an inch wide, 0’ 18 inch thick, and 5’4 inches long, and twisting it cold in the manner of 
a common twisted auger, twice round in the length just specified. The edges of the spiral 
were now exactly seven inches long. Hence, the elongation of the exterior fibres on the 
edges was 
0’7—5’4 
29’ 6 per cent. 
It is proper to state, that this experiment was made 
5’4 
