100 Experiments on two varieties of Iron. 



remaining on one of its parts, and the following results obtained, 



Viz. No. I, in original length of 6 inches had been elongated .87 in. = 14.5 pr. ct. 

 " 11, " " 4 " " .2 " = 5 " 



u III, « " 5 " " .6 " == 12 " 



" IV, " " 4 " " .2 " = 5 " 



To compare this iron with others, it is proper to assume bar 

 No. Ill, as the standard, that having been hammered till of a dull 

 red heat. The report already cited furnishes us with abundant 

 data derived from experiments made with the same machine, on 

 other kinds of bar iron in a similar state. Thus we have, 



lbs. per sq. in. 

 Iron from Salisbury, Conn., by a mean of 40 trials possessing a strength of 58.009 

 " Sweden, « 4 « u 58.184 



" Centre Co. Pa., " 15 " " 58.400 



" Lancaster Co. Pa., « 2 « " 58.661 



'• Mcrntyre,Essex Co. JY.Y.(as above) 4 " « 58.912 



" England, cable bolt, (E. V.) 5 " " 59.105 



«■ Russia, « 5 " " 76.069 



Hence it appears that the last only is essentially superior to the 

 Adirondack iron. These are among the best varieties of bar iron, 

 in point of tenacity. The second class will be mentioned below. 

 The fracture of No. I, is of a light gray color, has a silky lustre 

 and generally displays a compact structure. It is worthy of re- 

 mark that most of the fractures took place in directions oblique to 

 the line of tension, and making with it, either in the breadth or 

 thickness, one or more angles of about sixty degrees each. 



The fibrous structure of the metal was very marked in cutting 

 with the cold chisel, and was further developed by acids on a 

 part of the bar No. Ill, on the surface of which delicate lines 

 were shown traversing a distance of several inches. The specific 

 gravity in the annealed state appears to have been increased 1.2 

 per cent, by hammer-hardening. 



Experiments 07i specimen No. 2. 

 This was a bar one inch square and about two feet long. It 

 was first bent cold, till incipient fracture appeared on the outer 

 edges of the curved portion, which took Fi„. 3. 



place when the two limbs had approach- ^,,^~.-^^;;^^^:;;:;Z^ 



ed so as to make an angle of 30° with '\|^'' /y^ 

 each other. The exterior fibres in the ^^"^*Ovv 



part to which the change of form had , ^^^^^i^^ 



been confined, were then found to have ^"""^ 



