CClxiv GENERAL SUMMARY OF SCIENTIFIC AND 



localities suitable for the manufacture of Bessemer pig, and 

 which will doubtless be rapidly developed under the stimu- 

 lus of an increasing demand ; nevertheless the cost of mak- 

 ing pig suitable for this process is so much greater than the 

 cost of ordinary pig as to be a large item in a ton of rails. 

 The difficulty of controlling the amount of carbon is also 

 well known, and is a serious item in the cost. In every cast 

 made, the amount of carbon must be determined, sometimes 

 by chemical analysis, and again by tests of a mechanical nat- 

 ure. 



The Siemens-Martin method has the advantage of the Bes- 

 semer in these particulars : Irons containing a much higher 

 percentage of sulphur and phosphorus can be used, it being 

 estimated that about two thirds of the sulphur and three 

 fourths of the phosphorus are eliminated in the process. The 

 crop-ends of bars, scraps, all descriptions of waste, and old 

 wrought iron can also be utilized in a word, grades of pig- 

 iron that could not be used in the Bessemer process, and 

 much that would be waste, can be readily used. In the 

 Siemens-Martin process the quality of the product is com- 

 pletely under control. Should the metal at the time of test- 

 ing be too soft, more pig can be added ; while, if too hard, 

 simply waiting a few minutes will correct it. The loss in 

 the open-hearth process is considerably less than in the con- 

 verter according to Gruner, about one half. 



The decided advantage of the Bessemer process is the great 

 amount of steel produced per day, and the cheaper cost of 

 production. In some instances the amount has, with a pair 

 of 5-ton converters, exceeded 200 tons; while 10 tons would 

 be a good day's work with an ordinary open-hearth furnace. 

 With the Pernot modification of the Siemens-Martin furnace 

 there is a prospect that this objection may be overcome. It 

 is claimed that with Pernot's furnace 40 tons per day of 

 Siemens-Martin steel can be produced, and we have the au- 

 thority of an eye-witness for saying that the claim is well- 

 founded. If this is true, then with six of these furnaces a 

 product fully equal to that of a pair of 5-ton Bessemer con- 

 verters could be obtained. The cost of the plant would not 

 be more than half that of a Bessemer, the quality of the prod- 

 uct can be controlled with ease, pig-iron inferior to that re- 

 quired in Bessemer could be utilized, all scraps could be 



