[LB050052], Letter from Thomas Alva Edison to Pennsylvania Steel Co, Edgar Conway Felton, June 17th, 1891
https://edisondigital.rutgers.edu/document/LB050052
Transcription
June 17th, 1891. Pennsylvania Steel Co., E.C. Falton, Haq., Sup’t., Steelton, Pa. Dear Sir:- In reply to your letter of the 16th instant, I beg to say that provided you keep the carbon very low, for example below .13, it is indifferent what other elements are added, so long as the total impurity is say within half of 1%.In other words, you can add/phospohorus, manganese or silicon, sufficient to obtain a good casting, of course endeavoring to add only just what is required. Yours very truly, Thomas A. Edison M.