416 
Method of Hardening Copper. 
The pliosphorized copper is much more fusible than 
common copper : it may often he fused under charcoal 
powder without losing any of its properties. 
The same pliosphorized copper, when exposed a long 
time under the muffle, separates only with great difficulty 
from the phosphorus. 
The copper thus combined with phosphorus acquires 
the hardness of steel, of which it has the grain and the 
colour : like it, it is susceptible of the finest polish ; it can 
be easily turned ; it does not become altered in the air. 
I have kept buttons of polished pliosphorized copper in 
my laboratory for fifteen years, without their expe- 
riencing any alteration. The copper emits no smell 
when rubbed. Were it ductile, it would be of the 
greatest utility, since no fat bodies seem to have any hold 
of it. 
In the phosphorization of copper there is only a part of 
the animal glass decomposed, because a quantity of char- 
coal necessary to phosphorize the whole acid has not been 
employed : but it is necessary that this should be the case 
in order that the vitreous scoria should be sufficiently 
fluid for the phosphorus to be disengaged and to collect 
itself readily. 
The dark red enamel which is formed in this experi- 
ment may be employed with advantage for porcelain and 
enamels, as this red does not alter in the fire. 
Copper can combine with phosphorus only in the dry 
way. If a cylinder of phosphorus be put into a solution 
of nitrate of copper diluted with four or five thousand 
parts of water, copper under the metallic form will be 
found at the end of eight days crystallized and ductile, 
forming a case to the cylinder of phosphorus. 
