THE ST. JOHN'S RIVER, FLORIDA. 221 



found within the limits of the United States, for some reason, analysis has been 

 hitherto entirely overlooked, and we shall now endeavor to throw some light upon 

 copper from a chemical point of view. 



Comparative Purity of Copper. — Before proceeding to discuss the copper of 

 the mounds, early post-Columbian copper and native copper, it will be necessary 

 for the reader to have a clear idea of the percentage of pure copper usually found 

 in these commodities, that he may definitely draw his conclusions. 



Unfortunately, so far as the presentation of a striking case is concerned, the 

 difference between the purest of smelted copper and the most impure is relatively 

 small, its range not greatly exceeding two per cent., thus each tenth of one per cent, 

 is of marked importance. 



At the present time, with the most approved methods of smelting, a copper 99 

 per cent, pure 1 is considered of inferior grade, good commercial copper averaging, 

 let us say, 99 '5 per cent. pure. 



On the other hand, opinions of many experts, backed by results of analysis, 

 lead us to conclude that in early post-Columbian times commercial copper of a 

 much higher degree of purity than 99 per cent, was not produced in Europe. As 

 we shall see, lead was at that period intentionally introduced during treatment, 

 while arsenic and silver, loath to part company with copper, were not successfully 

 treated by the processes of those days. In fact, it is asserted that in recent years 

 old German copper coins have been profitably remelted for their silver, and yet it 

 was in Germany that smelting processes were best understood during early times. 



It is evident, then, that a copper purer than the average of that produced tinder 

 modem methods of smelting cannot have been derived from Europe during the six- 

 teenth or seventeenth centuries. 



The reader must bear in mind that analyses of copper from native metal, as 

 given in works on metallurgy and the like, are not results obtained from specimens 

 of mass copper prior to melting, but analyses made from ingots of cast metal which 

 may have lost proportions of certain elements during treatment, or received others 

 through accidental or intentional introduction. We have been unable in any work 

 to find the result of a single analysis of native copper made prior to the ingot 

 state, and have therefore submitted to various chemists a considerable number of 

 authentic specimens from different sections. 2 The percentage of p7tre copper in the 

 native state previous to treatment is from pp'6^, to ppy(p^. 



The Copper of the Mounds. — So great a period of time has elapsed since 

 the deposit of copper in the mounds that many of the sheets are carbonated and 

 oxidized through and through, rendering absolute determination as to purity impos- 

 sible. Where, however, a part of the metal remained we have been able to arrive 

 at definite results. 



1 At the present time "India sheets " and "brazier sheets," of a very low grade of copper, are shipped 

 from England to India and China. 



2 Since writing, our attention has been called to a statement by Rammelsberg (Mineralchemie, page 

 5) as to the impurities in Lake Superior copper. He reports iron - 31 per cent, and silver entirely absent ! 



