STRENGTH OF WROUGHT IRON. 



345 



THE STKENGTH OF WKOUGHT OE 

 MALLEABLE IRON. 



179- Of the various alloys and mixtures of iron used 

 in the arts, what is known a.s wrought iron is chemically 

 the most pure, usually containing about 99*5 per cent, of 

 chemically-pure iron The other ingredients are : Carbon, 

 of which there should not be more than 0'20 per cent, 

 present ; silicon, which should not exceed 0'20 per cent.; 



5 10 15 20 



Loads. Tons per sq. in. on original section. 



Fio. 169. TKNSIOX LOAD-STRAIN DIAGRAMS FOR WROI'UHT IRON. 

 A Lowmoor plate ; B High jri-ule bar. 



sulphur, phosphorus, and copper. If carbon or silicon 

 exist in the iron in greater quantities than those named 

 the iron will approach the condition of steel, and will be 

 rendered harder and less reliable. Suhoriur and copper, 

 even in very fcinall quantities, render the metal " hot 

 short," and difficult to work, while phosphorus has 

 the effect of making the iron " cold short," that is 

 to say, greatly lacking in ductility at the ordinary 

 temperatures. 



