EEPOBT ON BBOCKVILLE COPPEB IMPLEMENTS. 335 



lost art of native metallurgy in a previous communication,* the sub- 

 ject was remitted to me to report upon, with special reference to the 

 Brockville relics, which were put into my hands for the purpose of 

 experiment and analysis. 



The object of the following experiments, accordingly ,was to ascer- 

 tain whether the metal of which these implements are made is identi- 

 cal with the native copper of the Lake Superior Mines, or whether it 

 had been subjected to some manufacturing process, or mixed with any 

 other substance, by which its hardness might have been increased. 

 A careful examination establishes the conclusions here stated : 



lstly. No perceptible difference could be observed in the hardness 

 of the implements, and of metallic copper from Lake Superior. 



2ndly. The knife or small dagger, with a hook at the end, was 

 cleansed as far as possible from its green coating ; 



It weighed 32.440 grammes. 



It lost in water 3.741 " 



Hence its specific gravity is. 8.66 



A small fragment, broken off the end of the broad, flat implement, 

 described as a " copper knife of full size," having been freed from its 

 coating, was found to have a specific gravity of 8.58. 



During the cleaning of this fragment, a few brilliant white specks 

 became visible on its surface ; they appeared to be silver, from their 

 colour and lustre. The structure of the metal was also highly 

 laminated, as if the instrument had been brought to its present shape 

 by hammering out a solid mass of copper, which had either split up 

 or had been originally formed of several pieces. These laminas, of 

 course, contained air, and the metal was covered with rust, which could 

 not be removed, — hence the specific gravity would naturally be less 

 than if the metal had been dense. 



It is probable that the structure of the dagger previously referred 

 to, is the same ; but as the coating of oxide, which could not be re- 

 moved, would have more effect on the small fragment, which weighed 

 only about three grammes, than on the larger dagger blade, the specific 

 gravity of the latter was found to be rather higher. 



A portion of very solid copper, from Lake Superior, of about the 

 same weight as the fragment, was weighed in water, and its gravity 

 found to be 8.92 ; in this piece there were no cavities perceptible. 



The specific gravity of absolutely pure copper, varies from 8.78 to 

 8.96, according to the greater or less degree of aggregation it has. 

 received during its manufacture ; 



* The Ancient Miners of Lake Superior; ante, pp. 236, 237. 



