73 JOURNAL OF THE [Jul}'* 



Specimen No. 4 under the microscope is an etched piece of 

 metal from specimen No. i as it came from the ingot. Bright 

 lines forming polygonal structures enclosing the imperfect crys- 

 tals are quite distinct, while more delicate lines, extending from 

 the polygonal structures into the crystals, can also be seen at a 

 few points. The mottled appearance of most of the interior of 

 the crystals, caused by bright metallic points, may not, in the plane 

 of one etching, be traced to the polygonal lines. 



Specimen No. 5 is an etched piece from specimen No. 2. The 

 polygonal lines cannot be traced, because the coarse structure is 

 reduced. The bright lines are abundant and interspersed through 

 the steel in every direction as rather thick laminae. Specimen 

 No. 2, the test bar after testing, shows the steel to have a rough, 

 and reticulated surface on account of not being homogeneous. 

 This is the poor structure of soft rails and those which do not 

 wear well. 



Specimen No. 6 is an etched piece from test bar No. 3. The 

 bright lines are no longer distinct, but are well dispersed through 

 the steel, and the structure is homogeneous, which explains the 

 smooth appearance of the broken test bar. 



In specimen No. 7 — an etched piece of metal from a Bessemer 

 .50 carbon rail ingot by another method of treatment — the lines 

 forming the polygonal structure have been more deeply etched 

 than the other portions of the steel. 



The polyhedral structure of the Bessemer rail ingot is very 

 clearly indicated, as specimens Nos. 8 and 9 will confirm. The 

 ingot was not compressed, as that would add largely to the cost 

 of the rails and limit the output. • The same objections would 

 apply to subsequent heat treatment of the rails, and we are 

 obliged to resort to other methods of reducing the coarse struc- 

 ture in the ingot to a finer and more enduring one for the rails. 



The acid Bessemer process for producing steel is a very rapid 

 one, by blowing air of 25 to 28 pounds pressure per square inch 

 through a bath of molten cast iron in a converter to decarbonize 

 it, though really burning out first the silicon, then the carbon, 

 leaving in the bath the iron partially oxidized, all of the phospho- 

 rus, sulphur, copper, and traces of othar minerals contained in 

 the ores and fuel. To convert this molten metal into steel of the 

 required grade a definite weight of molten spiegel mixture is added. 



