NATURAL HISTORY of N RWAT, 195 



fetter, and according to the fame writer the produce of them has 

 been as follows; 



Svarkmae. 







Grudfetter. 





Ship- 



-pounds of 



Ship-pounds of 



Year. 



pure copper. 



pure copper. 



1720 



- 



722 



120 



1721 





694 



261 



1722 



- 



566 



263 



1723 





478 



210 



1724 



- 



401 



215 



SECT. VIII. 



The Indfet or Quickne copper-work lies ten Norway miles from The Indfet> 

 Drontheim, and though difcovered in 1635, was not wrought to °op^2St. 

 any great effect till 1707. Its ore is of eafier fufion than the 

 former, and has lefs ftone in it, but on that account is the more 

 faturated with fulphureous particles. A quintal of the ore yields 

 12 fhip-pounds of copper, which require a 100 lafts of coal, and 

 its annual produce is betwixt 3 and 400 fhip-pounds of metal. 

 The former director, M. Broftrup Fax, found out a method here, 

 by precipitation, to tranfmute iron into copper; the procefs of 

 which is thus : Near the caverns lie heaps of marcafites and fcoria?, 

 through which water is made to run into little channels filled 

 with bits of iron laid lengthways one below the other. This vir 

 triolic-water carries with it the copper fediment, and fometimes 

 copper itfelf, and permeates through the iron till at length it be- 

 comes copper. I have a fpecimen of this tranfmutation, though 

 fo far imperfect, that the internal part is ftill iron, and the furface 

 on all fides copper. Half a year is the term of a complete tranf- 

 mutation; but it mull be carefully attended, particularly with re- 

 fpect to the time, for if it mould lie a few days beyond the regu- 

 lar period, it would be fpoilt by the drofs and metal intermixing. 

 The iron fuffers a diminution in its weight, but this is compen- 

 fated in the profits of the tranfmutation. I remember Count 

 Marfilli, in his before-cited work, mentions a practice of this na- 

 ture at one of the copper- works in Hungary, where the vitriolic- 

 water, running from channel to channel, produces a like effect, 

 and has illuftrated his account of it with a copper-plate. 



E e e SECT, 



