AMERICAN INDUSTRIES SINCE COLUMBUS. 733 



on removal to be very crystalline and brittle. These changes of 

 structure and fracture were due to the absorption of carbon from 

 the charcoal dust in which the bars had been packed. 



Fig. 50 is a cross-section of a " cementation " or " blister-steel " 

 " converting furnace/' in which the various parts are so plainly 

 designated that additional description 

 is unnecessary. The degree of carburi- 

 zation, and consequently the hardness 

 of the steel produced in such a furnace, 

 necessarily varied, and for the conven- 

 ience of manufacture and trade the 

 product was assorted into six grades 

 or "heats."* 



When steel was wanted of closer 

 grain, firmer texture, and more reliable 

 character, a certain number of bars of 

 this "blister steel" were made into a 

 bundle or " fagot " and welded together, 

 and the resulting bar was called " sin- 

 gle shear " steel ; and if a still higher 

 quality was required, bars of "single 

 shear" were welded and drawn into 

 bars called " double shear steel." f 



Previous to the year 1812 we have 

 no record of there having been any 

 steel produced in America by other 

 than the processes already described, 

 but in that year John Parkins and his 

 son, Englishmen, " are said to have 

 made an unsuccessful attempt to make 

 cast steel in New York City," J and the 

 same authority tells us that they were employed, in 1818, at Val- 

 ley Forge, Pa., to make cast steel for a saw manufactory. 



In 1831 John R. Coates, of Philadelphia, stated that there were 

 then in the United States fourteen blister-steel furnaces, which had 

 " a capacity sufficient to supply more than sixteen hundred tons of 



* No. 1, spring heat, about | per cent carbon; No. 2, country heat, about per cent; 

 No. 3, single shear heat, about per cent ; No. 4, double shear heat, about 1 per cent ; 

 No. 5, steel through heat, about 1 per cent ; No. 6, melting heat, about 1| P er cent - 



\ Percy and other writers on the manufacture of steel have stated that the term 

 "shear steel" originated from the fact that such steel was used in making the blades of 

 shears ; but, as steel of the same quality was employed for multitudes of other implements, 

 and as " blister steel " was made in Germany before it was in England, it appears to the 

 writer more probable that the result of refining and improving its quality by successive 

 weldings received the German appellation of Sicher-stahl (sure, or trusty steel), which was 

 mistranslated into the English term " shear steel." W. F. D. 



\ Swank Iron in All Ages. 



Fig. 50. Cross-section of a Con- 

 verting Furnace for Blister 

 Steel. 



