.August 16, 1912] 



SCIENCE 



215 



scrap Tvhich they, in common with other open 

 hearth people, are obliged to use. They are now 

 well aware that ingot iron carries normally about 

 0.1 per cent, of copper, although efforts are being 

 made to reduce this, with some success. In the 

 meantime, they are explaining that their "99.94" 

 applies only to the usual impurities which have 

 been discussed in relation to the manufacture of 

 pure irons, such as carbon, manganese, sulphur, 

 phosphorus and silicon. 



Since the date of this letter, with the 

 writer's advice, The American Rolling Mill 

 Co. has reduced their purity guarantee to 

 99.84 in order to be certain to be on the right 

 side with respect to the small unavoidable 

 copper content. As a matter of fact, the 

 copper content of the pure iron product now 

 manufactured hy The American Rolling Mill 

 Co. is running normally 0.030 per cent, of 

 copper, or better. The elimination of copper 

 to this small percentage has been a matter that 

 has required expert chemical engineering and 

 very careful buying of raw material. At no 

 time has The American Rolling Mill Co. ever 

 introduced copper into their material except in 

 the case of three experimental heats which 

 were made under the supervision of the vsrriter 

 with the intention of determining what ef- 

 fect, if any, the introduction of small amounts 

 of copper would have upon the qualities of the 

 material. Subsequent tests showed that the 

 introduction of copper into iron served no 

 good purpose, and therefore the effort by The 

 American Rolling Mill Co. to completely elim- 

 inate it has gone on with unremitting zeal. 



From a commercial point of view, it is per- 

 haps not to be wondered at that the attempt to 

 manufacture an extremely pure iron on the 

 same large scale of operation usual in steel 

 manufacturing should have aroused the bitter 

 enmity and active hostility of competing in- 

 terests in this country. It is, however, cer- 

 tainly unfair to the efforts which have been 

 made to establish the pure open hearth iron 

 industry for the first time in the United 

 States or, in fact, in the world, to have scien- 

 tific literature distributed with the intent to 

 produce the impression that the object of the 

 manufacturer is not to produce a pure ma- 



terial but to load it with another metal for an 

 ulterior purpose. If Professor Walker had 

 taken the trouble to inform himself in regard 

 to this question as late as April, 1912, he would 

 have discovered that the normal heats of the 

 pure iron made by The American Rolling Mill 

 Co. do not contain more than .03 per cent, of 

 copper, for any one interested in investiga- 

 tions along this line is welcome to obtain his 

 own samples directly from the mill in which 

 the material is being manufactured. 



The total elimination of copper from a highly 

 refined iron is not an easy metallurgical prob- 

 lem. The charge for the open hearth furnace, 

 whether steel or pure iron is to be made in it, 

 is normally a mixture of pig iron and selected 

 scrap. If the object is to refine the mixture 

 so as to produce a commercially pure iron, 

 very special attention has to be paid to the 

 amount of copper which may be carried in 

 the raw material. Open market iron of the^ 

 present day is likely to carry much more copper 

 than was formerly the case. This is largely 

 due to the fact that the introduction of lifting 

 magnets for loading and unloading, has made 

 available in the metallurgical arts, machine 

 shop turnings and other useful sources of iron. 

 From the conservation point of view, a move- 

 ment of great value has therefore been de- 

 veloped by the use of the lifting magnet. 

 Since, however, copper is not in the slightest 

 degree eliminated in the refining processes of 

 the open hearth furnace, unusual care has to 

 be taken in selecting raw material, to see that 

 it is not contaminated with copper. Owing to 

 the increased uses of copper and bronze in 

 bearings and other parts of machinery, even 

 so-called "heavy melting stock" is likely 

 to carry unknown quantities of copper. 

 Nevertheless, by careful selection of scrap and 

 pig iron used in the processes, and by paying 

 more for selected materials, it is possible by 

 the exercise of continuous vigilance to keep 

 the copper content down to a minimum point. 



It is a curious fact that while The Ameri- 

 can Rolling Mill Co. has been making every 

 effort to fight copper and keep it at the lowest 

 possible point, a number of the steel manu- 



