1892.]. NEW-YORK MICROSCOPICAL SOCIETY. 75 



upon the side, the drop of 2,000 pounds falling 20 feet upon the 

 upper edge of base and side of the head, causing; the lower edge 

 of the base to elongate 18 per cent per inch for at least 6 inches 

 in length. The rail rebounding from the blocks after the drop 

 struck, it dropped to the foundation of the ingots supporting the 

 blocks, the base wedging between two ingots. The fall of the 

 rebounded drop broke out this piece containing the inch spacings. 

 The fracture in this case is much coarser than would have been 

 the case had the rail failed under the full drop. 



Specimens Nos. 15, 16, 17, 18, and 19 are longitudinal sections 

 of pit-test ingots, showing the piping and the gas cavities which 

 are liable to form. In rolling these for bending tests they are 

 not allowed to cool and some of these cavities are closed. 



Nos. 15, 16, and 17 are from the same heat of steel, Nos. 15 

 and 16 being the parts of the same ingot. 



Specimen No. 17 is an ingot on which I made the experiment 

 of seeing how much additional carbon would be absorbed by hav- 

 ing one side of the mould a plate of carbon. The steel, as poured 

 into the ingot, contained ,48 of carbon, was chilled in less than 

 ten minutes, remained in the mould and was cooled in two hours. 

 The first sixteenth inch averaged 1.48 of carbon, the second 

 sixteenth inch .81, and the third was nearly normal. This 

 shows a very rapid and unexpected rate of absorption of carbon, 

 and we can readily understand the diffusion of carbon from the 

 walls surrounding crystals to the crystals, or vice versa, at tem- 

 perature below fusion. This can also be understood by the pro- 

 cess of cementation imparting carbon to iron plates, to make 

 crucible steel. The process of making molten steel take up an 

 additional amount of carbon by absorption pernlits of graduations 

 of carbon in the same ingot. 



Specimens Nos. 18. and 19 are from the same heat of steel, 

 though in No. 18 a small amount (one hundredth of one per 

 cent) of aluminium was added to see its effect upon lessening the 

 blow holes and gas cavities in the steel. The former were re- 

 duced, the latter prevented, though the pipe of the ingot was in- 

 creased. The tensile strength and elongation of the metal were 

 slightly augmented. 



With the rapid output of the rail mills, and only 1 1 passes in 

 the rail trains, it seems important, in order to secure a good 



