632 CENTRAL MINERAL REGION OF TEXAS. 



long successfully used in iron metallurgy abroad. If further practical tests 

 now under way upon a large scale confirm those already made, the delivery 

 of this fuel may perhaps be feasible at such cost as to enable local smelting 

 to become profitable. The laying down of gas coal or coke in the district at 

 any price which can maintain competition with distant points now cheaply 

 supplied, is at least a remote possibility, without the construction of many 

 miles of new railroad. Whether this can change the smelting conditions is 

 somewhat doubtful, because there are already so many well established trade 

 centers which can divert the trunk lines from this region. 



But without further discussion of this important topic, there are mining 

 and metallurgic issues of moment which are well worthy of consideration by 

 all interested in the iron district. The differences in the value and the cost 

 of working of the several classes of ores are very great under the most favor- 

 able circumstances. Below are given some hints which may be useful to 

 those who do not understand the requirements of the furnaces. 



1. The pig iron produced in the blast furnace from the hard ores (mag- 

 netite and hematite), in order to be generally used in the ordinary (acid) 

 Bessemer steel process, should not contain above .22 per cent of phosphorus 

 (say .5 per cent of phosphoric acid), and that amount is too liberal an allow- 

 ance for many purposes. This is not saying that ores with higher percentages 

 of phosporus can not be successfully smelted, but ordinarily they would not 

 be found to be desirable, because we have not a class of ores suited to treat- 

 ment by the basic process, which requires more phosphorus. Our ores are 

 remarkably free from phosphorus, except in localities where they lie near the 

 greensands and in special layers like No. 19, Table III. In the Central 

 Mineral Region the unusually high phosphorus ores can always be separated 

 in the mining, and those which come near the permissible limit can be mixed 

 with the best ores at mine or furnace so as to bring the percentage down 

 below the maximum. 



2. The soft ores of our district can be advantageously mixed with the 

 hard ores in the production of different grades of pig iron, but they are less 

 abundant and more difficult to obtain than the hard Bessemer ores. The 

 soft ores frequently contain more phosphorus, especially in their passage 

 through the greensand horizon of the Cambrian System. Suitable mixtures 

 of these will be more difficult to effect at the mines, because the vein product 

 is generally uniform in each locality. But the limit of phosphorus allowable 

 is, much higher in iron metallurgy, owing to the wide range of application of 

 the product and the facility with which phosphorus may be expelled in the 

 puddling or other processes of refining. 



3. There is little or no application of the Thomas or basic Bessemer pro- 



