134 Wisconsm Academy of /Sciences^ Arts, and Letters. 



which turn out excellent articles, one in London which makes 

 the celebrated Plumbago crucible. It will sufficiently indicate 

 the difficulties involved, when I state that America, to-day, is de- 

 pendent upon Europe for the immense number of crucibles used 

 in this country. I am aware there is a manufactory established 

 in Connecticut, but the quality is so inferior that they are only 

 used for the more easily fused metals. I experimented with frag- 

 ments of pottery taken from the ancient mounds near Eacine, in 

 order to determine the degree of heat they would stand. The 

 result was they were melted long before the copper was 

 fused. 



A majority of copper implements found have specks or points 

 of pure silver scattered over their services. I am prepared to 

 prove by the best authority in America, James C. Booth, and 

 Thomas H. Garrett, TJ. S. assayers at Philadelphia, that one sin- 

 gle speck of pure silver, visible even with the microscope, is 

 positive evidence that the specimen was never melted. 



Copper unites intimately with nearly all metals, thus form- 

 ing homogeneous alloys — with zinc forming brass, with tin, 

 bronze, and so on. The only apparent exception to this law is 

 where large masses are fused and at rest for a long time. In these 

 cases the heavier metals gravitate and separate more or less, but 

 never perfectly. When large brass cannon are cast, in consequence 

 of the great quantity of metal fused, together with the additional 

 circumstance that the mould is made in the earth and hence re- 

 quires days to cool, "blotches of lighter color are occasionally 

 found on the surface of the guns, indicating a segregation of the 

 metals. A fibrous texture is another evidence that these imple- 

 ments were hammered or rolled out. This fibrous quality is well 

 exhibited by the action of strong acids on the specimens. On 

 articles that are cast, the acid acts in a uniform manner, revealino- 

 no striae or hard bands. The absence of the slightest indication 

 of ^sprue~t\e opening where the metal is poured-is also to 

 say the least, suggestive. We certainly would expect to find'in- 

 dications of this necessary blemish in specimens so carelessly fin- 

 ished that the mould marks remain conspicuous. If these pro- 

 jections are the remains of the imprint of the mould, the specimen 



