THE IRON SERIES (IN PART). 71 



record shows that 40,000 tons of magnetite averaged 68.6^ 

 Fe. In general the ores run much less. The richest are the 

 magnetites and specular hematites. In numerous instances the 

 mines of the Lake Champlain district have produced the former, 

 and Lake Superior mines the latter, at 63 to 65$, or even more. 

 The separated ores in the Lake Champlain district run about 65$. 

 The unseparated ores have much less, and indeed all percentages from 

 50 to 65. Thus the lump ore (shipped as mined) from Chateaugay, 

 N. Y., has about 50$. The Cornwall (Penn.) magnetite holds even 

 less. The Clinton red hematites from New York afford about 44$ in 

 the furnace, as the result of long experience. The limonites, as usu- 

 ally mined, produce from 40 to 50$. The crude spathic ores are the 

 lowest of all, and in the variety black-band may even be about 30$. 

 They are easily calcined, however, and on losing their carbonic 

 acid, moisture, and bituminous matter the percentage of iron rises 

 a third or more'. A. H. Chester found in 1875, as the result of an 

 endeavor to determine the average yield of certain standard ores in 

 the furnace, Lake Superior specular, 62.5$ ; Lake Superior limonite, 

 49.5# ; Rossie (K Y.) red hematite, 54.5$; Wayne County (N. Y.) 

 Clinton ore, 40l 



2.01.02. The common impurities in iron ores are the common 

 elements or oxides that enter most largely into rocks, and those 

 which make up the walls of the deposit are usually the ones that 

 appear most abundantly in the ore. Silica (SiO 2 ), alumina (A1 2 O 3 ), 

 lime (CaO), magnesia (MgO), titanium oxide (TiO 2 ), carbonic acid 

 (CO 2 ), and water (H 2 O) appear in large amounts and determine to 

 a great extent the character, fluxing properties, etc., of the ore- 

 With these, and of more far-reaching influence, are smaller amounts 

 of sulphur and phosphorus. The last two and titanium chiefly de- 

 termine the character of the iron which is yielded in the furnace 

 and are the first foreign ingredients sought. The sulphur is present 

 in pyrite, the phosphorus in apatite. As is well known, 0.1$ of 

 phosphorus is set as the extreme limit for Bessemer pig irons, and 

 as ores for these command the best market, they are eagerly 

 sought. To obtain the allowable limit of phosphorus in the ore, its 

 percentage in iron is divided by 1000. Thus a 65.3$ ore should 

 not have over 0.065$ phosphorus to be ranked as Bessemer. If at 

 the same time, with sufficiently low phosphorus, the gangue is 

 highly siliceous, a composition desirable for Bessemer practice, 

 ores may be of value, although of comparatively low grade and re- 

 motely situated. 



