52 MILD STEEL. 



give the first place by reason of tlie many advantages it 

 possesses over wrought iron. 



Mild steel is capable of being manufactured with almost 

 absolute certainty in correspondence with any analysis 

 within its range, and in such large quantities that great 

 nniformity of composition is attained. Having been in a 

 «tate of complete fusion, it is homogeneous, fi'ee from lami- 

 nations and blisters, and has no entangled slag in it, whicli 

 was far from being the case with iron, so that for boiler 

 furnaces and the like the above characteristics render steel 

 by far the most suitable material. Moreover, the plates 

 being thinner are better conductors of heat. Steel plates 

 can be produced of much larger size than iron plates without 

 the same risks of being defective, and consequently there are 

 required fewer seams and joints, which is a great advantage, 

 particularly when thick plates are employed. 



It is practically of equal tenacity in every direction, an (J 

 when worked by experienced men is less liable to crack or 

 injury v/hen being flanged. Although my experience with 

 steel is limited to boilers of comparatively recent construc- 

 tion, I believe this material is not subject to " pitting" to 

 anything like the extent we have been accustomed to in 

 iron boilers, which no doubt is due to the absence of slag 

 and other impurities, which are found to exist to a very con- 

 siderable extent in all iron plates, especially those of inferior 

 manufacture, or when the heat used for "pile" has been 

 insuflicient to render the cinder perfectly fluid. In this 

 connection I may mention that it has been stated that steel 

 stays in the steam space, and steel plates subject to the 

 a,ction of water leaks under pressure, corrode far more 

 rapidly than do those of iron ; whilst on the other hand it is 

 claimed for-the steel that scale or dirt does not adhere so 

 firmly as with iron, and that the comparatively pure water 



