£72 On the Art of Hardening Copper. 
harder: but thefe properties are foon loft when the copper is 
melted in contaét with carbonaceous matter. If melted cop- 
per be poured into water, as is done in the operation of gra- 
nulating or corning g, it does not appear that it acquires any 
perceptible degree ‘of hardnefs, or fuch as can be compared 
to that which is communicated to fteel by the fame means. 
Confidering all thefe circumftances, which have been con- 
firmed by experience, it could not but excite attention to 
find, by the moft undoubted teftimony, that the ancients 
actually poffeffed the art of hardening copper, which they 
employed for inftruments of all kinds; fuch as daggers, 
fwords, bows, fhields, javelins, &c. Thong ancient au- 
thors often mention thefe weapons, none of them have given 
us.any account of the method of hardening the copper. This 
deficiency fome have attempted to fupply by conjectures, 
which have given rife to a variety of experiments, but not 
one of them was ever attended with fuccefs. As it was 
imagined that in hardening copper it would be neceffary to 
follow the fame procefs as that employed for. fieelifying 
iron, moft of their refearches have been direéted to a fimilar 
method; and for that purpofe they have not only preferibed, 
for the hardening of copper, fuch procefies as are employed for 
hardening iron when it is to be converted into fteel, but even’ 
the moft abfurd methods founded upon thefe procefies. Thefe 
refearches, however, inftead cf anfwering the intended pur- 
pofe, only tend to fhew the ignorance of thofe who think 
they find in the greateft abfurdity the moft important fecrets, 
and to involve us in ftill greater darknefs. 
The art of hardening copper has therefore of late been 
’ confidered as one of thofe known to the ancients, which were 
afterwards loft; and it would no doubt have ftill remained in 
that ftate, had not feveral of thefe monuments of our ancef- 
tors been brought to light by fome fortunate accidents, and- 
the refpeét for their great antiquity been overcome by a defire 
for becoming acquainted with their compofition, When 
this method, the only certain and decifive one, was once 
chofen, it was no great difficulty to difcover that the whole 
art did not depend on any procefs like that employed in re- 
gard to iron, but on the addition of a certain quantity of 
9 fome 
Me Fg eC 
