142 BULLETIN 12, irNITED STATES NATIONAL MUSEUM. 



has accuiijulated. About three hours are lequired to produce the 

 proper sized loupe. This loupe is taken out of the tire and into the 

 hole left a suitable amount of ore is thrown and the process of reduc- 

 tion continued. The loupe is taken to the hammer and is hammered to 

 consolidate the iron and expel the slag. One end is fiuished to 7 inches 

 square, and the other end is put back into the furnace to heat it up 

 again, which does not interfere with the operation of the furnace. 

 When the bloom is hot enough It is taken back to the hammer and the 

 other end finished to 7 inches. In some cases this 7-inch bloom is re- 

 duced to 3.^ inch billets. 



A good workman will produce a ton of blooms with 250 to 200 

 bushels of charcoal, and a ton of billets with 312 bushels, but these 

 figures are often exceeded. 



A general interior view of the forge is shown in pl. xii the trip 

 hammer in pl. xiii, and a general collection of tools used in PL. xiv. 



During the smelting operation two characters ot slag are produced, 

 depending ui)on the temperature of the fire. AVhen the fire is hot the 

 slag is very vesicular ^md gives oft" jets of gas. When, however, it is 

 cold, the slag flows quietl}" and is compact. Thero are formed also 

 two byproducts. One, known as coal crust, consists of a mixture of in- 

 fusible slags, iron, and coal, and gathers on the top of the slag. The 

 other, known as emery, consists of fine material carried forward by 

 the blast and collected in the chimney. 



The collection joins the Eogersfield Mine collection, which supplies 

 the ores, and was also taken by Mr. J. B. Mackintosh, e. m., August, 

 ]884. 



(1) Wood, maple ; used for making cTjarcoal. (r)41*JL) 



(2) Charcoal, used for fuel. (rj4102.) 



(:{) Irou, a test button taken from the furnace to observe its workings. (5411)0.) 



(4) Cinder, from hot furnace, (54136.) 



(5) Cindei", from cold fnrnace. (54187.) 



(()) Cinder, scjueezed from the bloom in hammeriDg. (54189.) 



(7) Scale, prnduced in hammering the relieated bloom. (5418^.) 



(8) Coal crust. (54184.) 

 <!)) Emery. (54185.) 



The Manufacture of Steel. 



A small amount of steel is made direct from the ore, but, as in the 

 case of wrought iron, nearly all is made from pig iron that has been 

 reduced in a blast furnace. 



Since the main difference between pig-iron and steel lies in the different 

 percentages of carbon they contain, the process of steelmaking should 

 simply be tlie removal of the proper amount of carbon from i)ig iron 

 containing oidy small amounts of impurities, and (liis is sometimes the 

 case, but it is far moi'e frequent to remove as much as possible of the 

 carbon and tlien to add just the right amount, this being easier than 

 to remove just the right amount at once. 



