MODERN BLACKSMITHING 119 



hard as it will without drawing the temper, the heat to 

 be a low red cherry. Diluted muriatic acid is a good 

 thing to roughen the surface with where you want the 

 hole. Use kerosene instead of oil, or turpentine. The 

 pressure on the drill should be steady so that it will 

 cut right along as it is hard to start again if it stops 

 cutting, but if it does, again use diluted muriatic acid. 

 The hole should be cleaned after the use of the acid. 



FACTS ABOUT STEEL 



I have repeatedly warned against overheating steel. 

 Don't heat too fast, for if it is a piece of a large dimen- 

 sion the outside corners will be burnt, while the bar is 

 yet too cool inside to be worked. Don't let steel 

 remain for any length of time in the fire at a high heat, 

 for both steel and iron will then become brittle. This 

 is supposed by some to be due to the formation of oxide 

 disseminated through the mass of the metal, but many 

 others believe that a more or less crystalline structure 

 is set up under the influence of a softening heat, and is 

 the sole cause of the diminution in strength and tenac- 

 ity. The fiber of the steel is spoiled through over- 

 heating; ■ this can, to some extent, be remedied by 

 heavy forging if it is a heavy bar. 



Steel is harder to weld than iron, because it contains 

 less cinders and slag, which will produce a fusible fluid 

 in iron that will make it weld without trouble. Steel 

 contains from 2 to 25 per cent carbon, and varies in 

 quality according to the per cent of carbon, and it is 



