THE ST. JOHN'S RIVER, FLORIDA. 239 



These analyses are complete. Dr. Keller informs us that the shortage was 

 due to the oxygen present as oxide of copper or of iron resulting from superficial 

 oxidation. 



Some of our readers will recall that extensive aboriginal mining operations 

 were carried on at Isle Royale, in Lake Superior. We are indebted to Professor 

 Edgar Kidwell, of the Michigan Mining School, for a specimen of copper from this 

 island, which, submitted to- Dr. Keller, was reported upon by him as follows: — 



" The material was very carefully separated from the rock through which it 

 was disseminated. It retained 0-2561 per cent, of insoluble matter. An exhaustive 

 examination of the metallic portion yielded the following values : — 



Copper 



. 99-9314 per cent. 



Silver 



. 0-0271 



Iron 



0-0068 



Nickel 



. 0-0037 



Arsenic 



Trace. 



99-9690 



" Gold, lead, tin, bismuth, antimony, cobalt, manganese, oxygen, sulphur were 

 tested for with negative result. The absence of other metallic impurities was indi- 

 rectly ascertained in the course of analysis adopted. 



"The specific gravity is 8 - 883." 



Dr. Keller has made for us a partial analysis of copper in his possession, from 

 the Phoenix mine. Of this he writes : — 



" The specimen from this celebrated locality was beautifully crystallized. It 

 contained - 962 per cent, of quartz, and after deducting this yielded : — 



" Copper ..... 99'9462 per cent. 

 Nickel ..... None. 

 Arsenic ..... Trace. 



"This copper contains iron but scarcely a trace of silver." 



We are indebted also to Dr. Keller for copper from the Quincy mine, Hancock, 

 Mich. We append the result of a partial analysis made by him. 



" Copper .... 99'9765 per cent. 

 Nickel .... None. 

 Arsenic .... None. 



" Silver and iron are the only impurities, a strong reaction was obtained for 

 the former, while the latter is present merely as a trace." 



Professor James Douglas, who has so greatly aided us in this paper, has pre- 

 sented us with specimens of copper from the Quincy, Atlantic and Central mines of 

 the Lake Superior District. These have been submitted to Ledoux and Company 

 for partial analysis, who report : — 



" Quincy Mine, Lake Superior : — 



"Copper .... 99 - 93 per cent. 

 Nickel and cobalt . . None." 



30 JOURN. A. N. S. PHILA., VOL. X. 



