TKANSACTIONS OF THE SECTIONS. 205 



Now, as regards the question of toughness and malleabilit}', and referring again 

 to Mr. Kirkaldy's experiments, it appears that in the tests of " Bessemer steel " 

 eighteen samples were tried under tensile strain, the length of the samples being 

 in round numbers 50 inches, and the diameter 1-382 inch ; and that when these 

 were subjected to ultimate strain, tlie elongation at the moment of fracture was 

 in the most brittle example 2J inches, but generalh' varied from 4^ to 9^ inches. 



In the experiments on transverse strain, in wldch the bars were nearly 2 inches 

 square and only 20 inches between the points of support, all the " Bessemer 

 steel " samples, except two, bent 6 inches without any crack. Again, in the 

 experiments made by the Committee on bars 14 feet long and 1^ inch in diameter, 

 out of twenty bars of the milder quality of steel, sixteen extended more than 8 inches, 

 and of these ten extended more than 12 inches. 



As another example of the malleability of steel, I may mention that I have 

 seen a piece of rail, weighing 80 lbs. per yard, and 12 feet in length, held by one 

 end and twisted at the other, until it made 6f complete revolutions before it 

 broke. The fracture occurred at one end, leaving about 11 feet of the rail in the 

 twisted form which had been given to it. 



In this twisted state the rtnl was laid on two bearings 3 feet G inches apart, 

 and subjected to the blow of 1 ton weight falling 30 feet, and it bore one of these 

 blows without breaking. 



I have also used a considerable quantity of steel rails, the test to which they 

 were subjected being 1 ton falling 20 feet on a 3-feet 6-inch bearing, and out of 

 tlie whole number tested there was not one which broke with this test. The 

 effect of the blow was to produce a set of about 2| inches ; and if the rail was then 

 reversed and struck on the other side, it became nearly straight again. As a rule, 

 the rails yielded to the third blow ; but I have seen seven blows given without 

 producing fi-acture. 



(Jn the other hand, five of the bars tested by the Committee were of inferior 

 malleability. 



We have also instances in which steel rails break with the jar produced by 

 being thrown off the waggons on to the ballast ; and there is no doubt of the fact 

 that steel is made and sold which is cold-short, and not reliable for use for 

 engineering purposes. This irregularity appears to arise mainly from the dif- 

 ference in the chemical constituents of the metal or ores employed, or in the process 

 pursued by difterent makers. 



Another element of uncertainty appears to be that, in these modern and rapidly 

 made steels, the precise time allotted to the several stages of the process, the 

 degree of heat "employed, and a variety of other circumstances have to be carefully 

 observed, and any inaccuracy in carrying out the required conditions affects the 

 quality of steel produced. 



Nevertheless it is known that in the Bessemer process, if ores or metal of suit- 

 able chemical qualities are used and the process of manipulation is properly per- 

 formed, the quality of metal produced is certain and regular in its results. 



In the processes of Dr. Siemens there is not the same necessity for purity in the 

 ore or metal required, the nature of the process being, I believe, such as to 

 eliminate some of the ingredients which would prevent toughness being obtained, 

 while tests may be made during the process of manipulation so as to ascertain 

 that the metal is of the quality sought before it is run off into the ingot-mould. 



Where large castings and metal of great solidity are required, as in making large 

 gims, there is the method pursued by Sir J. Whitworth, whereby the metal is 

 intensely compressed while in a tluid state. 



The pressure employed is 20 tons per incli, and its effect in producing solidifica- 

 tion is such as to shorten the ingot about 1^ inch for every foot of length. 



The treatment by compression is especially important where metal is required in 

 large masses and of great ductility, because the larger the mass and the greater the 

 ductility, the larger and more numerous are the air-cells, and the effect of the pressure 

 is to completely close these cells and render the metal perfectly solid. 



By this process mild steel can be made with a strength of 40 tons to the inch, 

 having a degree of ductility equal to that of the best iron. 



The more highly carbonized qualities, whose strengths range from 48 up to 72 



