THE USE OF IRON. 63 



ing all the good characteristics of wrought iron, with greater 

 strength and toughness, and it seems probable that it will be 

 extensively used in the future." 



According to Campbell, the German specifications in most 

 general use call for the following physical conditions : 



"For rivets: Ultimate strength from 51,200 to 59,700 

 pounds per square inch; elongation, 22 per cent, in eight 

 inches. 



" For other structural material : Lengthwise tests, ultimate 

 strength from 52,600 to 62,600 pounds per square inch; elon- 

 gation, 20 per cent, in eight inches. 



"Crosswise tests: Ultimate strength from 51,200 to 

 64,000 pounds per square inch; elongation, 17 per cent, in 

 eight inches." 



Commenting upon these requirements, Mr. Campbell says : 

 "It is safe to say that if American engineers were satisfied 

 with the German standards, there would not be one rejection 

 for deficient ductility where there are twenty under our more 

 rigid requirements ; and if they would be content with a steel 

 having an ultimate strength between 52,000 and 62,000 

 pounds per square inch, there would not be one-fifth the 

 number of heats discarded for being outside of the tensile 

 limits. The bearing of these facts upon the cost of the ma- 

 terial is self-evident. 



" I do not advocate any sacrifice of strength to economy, 

 but I would impress upon the American engineers that this 

 soft metal is eminently 'suited to structural work, while by 

 maintaining their present chemical limitations and their re- 

 quirements concerning ductility, they will be assured of a 

 material which is equal in quality to any produced in the 

 world." 



In a recent publication, one of the largest manufacturers 

 of structural steel records his conclusions as follows: 



"The strength of structural steel depends largely on the 



