1894.] NATURAL SCIENCES OF PHILADELPHIA. 313 



length and breadth, do not vary materially, so that the measurement 

 of one, namely 2-5 inches by 3"2 inches, may be considered to apply 

 approximately to all. That they had been portions of a sheet or 

 sheets of larger size was evidenced by at least one closely ground 

 edge on each specimen, contrasting markedly with the rough line of 

 separation of the other margins. No ornamentation like the beaded 

 margin and the repousse work of Florida and Tennessee was 

 apparent, though the marks of numerous blows from a convex blunt 

 cutting- edge were visible on all the specimens. Exfoliation was 

 noticeable near the edges. The sheets were of irregular thickness 

 averaging about 1 mm. 



Notwithstanding these indices of aboriginal origin, so solid was 

 the appearance of the copper that, though no believer in a post- 

 Columbian origin for mounds as a rule, I admit having experienced 

 a feeling of doubt as to the origin of this copper, a doubt which a 

 thorough and careful analysis, made by Ledoux and Company, of 

 New York, speedily dispelled. The result is given in detail: — 



"Copper 99-9130 



Silver 0-0198 



Arsenic 0-0026 



Antimony Trace 



Iron . ." 0-0233 



Nickel and cobalt .... 0-0080 



"Note: — The above analy.sis was made after removing the super- 

 imposed film of oxides and carbonate from the sample. Special ex- 

 amination fur lead, bismuth, and zinc shows that none of these is 

 present. ' ' 



It is quite evident that here we have to do with native copiper of a 

 purity greater than is ordinarily produced at the present time by any 

 smelting process^ and consequently of a still higher degree of purity 

 than would be the product of early processes of smelting the arsenical 

 sulphide ores of Europe*. ^.loreover, the introduction of lead in 

 refining, though not an invariable custom, was extensively practised 

 iu Europe, especially in copper intended for sheet or wire, and its 



^ All smelted copper contains from three to ten lunulredths of one per cent, 

 of combined oxygen. • 



* For full details as to aboriginal copper the reader is referred to "Certain 

 Sand Mounds of the St. John's Eiver, Florida, Part II," Journ. Acad. Nat. Sci . 

 Vol. X. 



