On the Art of Hardening Copper. a3 
. fome other metal melted with the copper, by which it was 
rendered harder than before. 2 
The abbé Mongez firft wrote a treatife on the metallic 
compofition of the ancient bells, which he tranfmitted to the 
Academy of Infcriptions. He found that this compofition 
was in general nearly the fame as that ftill ufed for bell-me- 
‘tal, that is, copper and tin. M. Mongez afterwards tranf- 
mitted to M. Dizé the point of an ancient copper dagger, 
the appearance of which on the fracture fufficiently fhewed 
that it had been fufed and caft. When diffolved in pure ni- 
trous acid, there remained a white powder, found to contain 
tin, and that which had been diffolved was merely copper. 
It evidently appeared, therefore, that the fuppofed art of the 
ancients for hardening copper, was nothing elfe than fufing 
_ it with a certain quantity of tin. This was ftill farther cons 
firmed when M. Dizé found the fame component parts in 
fome Greek, Roman, and Gallic coins, which he obtained 
on the fame occafion for the purpofe of examination. The 
tin in them formed about twenty-four parts in a hundred of 
the mixture. 
- In fupport of this opinion, refpecting the art of hardening 
copper among the ancients, I have the honour of laying be- 
fore the Academy fome experiments lately made on this fub- 
ject.—Latt faummer, Profeffor A. I. Retzius, of Lund, tranf- 
mitted to me a part of the blade of a two-edged dagger, 
which, together with-fome ftone-cutters’ chiffels, were found. 
in a hill of earth on the low lands of Scandinavia, where 
whole fwords of ancient workmanfhip have often been found. 
This fragment, on the outfide, had rather a yellowifh appear- 
ance like brafs, than the red colour of copper; the edge was 
exceedingly thick, and_roundifh; the fraéture feemed alfo 
granulated, which evidently fhewed that the work had been 
caft, When tried by the file, it was not quite fo hard as the 
common bell-metal, but fomewhat harder than common 
gun-metal. The newly-filed furface had a reddith-yellow 
appearance, but foon became yellower. When melted by 
the blow-pipe, this compound metal exhibited no traces of 
zinc; butit might be readily feen, by its appearance, that the 
greater part of the mixture was copper, The filings were 
Vou, V. Na not 
