National Industry (in France). 231 
which could be advantageously employed in bars, in plates, or 
in moulds. . 
M. Dussaussoy *, who has made known that a mixture of cop- 
per, tin and iron, produces a compound of great tenacity, much 
hardness, easily wrought, and excellent for cannon, indicates 
many other compositions, which, according to the proportion of 
the metals and the thickness of the pieces cast, lose or gain, 
sometimes in tenacity, at others in hardness, qualities which may 
often be augmented by tempering and hammering. Such com- 
positions have not been adopted into modern use, but may how- 
ever be of great utility to the arts. It may be sufficient to cite 
that compound of the ancients, consisting of 14 parts of tin to 
100 of copper, which cold-beaten and sharpened produced blades 
harder than iron, and even preferable to those fabricated with 
certain varieties of steel. 
If the irons and steels employed are further examined one by 
one, it will be found that the steels are generally less oxidizable; 
but that there are among them some more so than others, which 
renders it of consequence that we should be select in our choice— 
that the parts not exposed to friction may be greatly protected 
from rust, by smoking them, by giving them a strong varnish, by 
tinning, or by oxidizing the surface before hand with acids, as is © 
often done with fire-arms; or by a method still better than any 
of these, by keeping them under water for a certain time, from 
which they will come out with a sort of varnish less injurable by 
humidity, and similar to that which the fowling- piece of a game- 
keeper acquires after long use. 
Iron is in another state naturally much less oxidizable, namely, 
when fused. From the facility with which it may be then moulded, 
and from its hardness, it appears capable of being beneficially 
employed for all the friction parts of instruments, by fabricating 
with it surfaces covered with sharp points—asperities artfully 
disposed—so as to form excellent rasps for the grating of fruit and 
escnlent roots. Cast-iron may also be used for the other parts 
of such instruments, by moulding them with such precision that 
the file shall not be necessary to adjust them, and the surface of 
the moulding be thus preserved, which is always harder and much 
less oxidizable than the interior. When machines of this descrip- 
tion are not in use they ought to be deposited in dry places, 
being first covered with a sort of soap formed of oil mixed with 
quick lime, and then powdered over with lime, which will serve 
to absorb the humidity and the acids. 
It is to be hoped that by such means advantageously combined, 
and by others known to or which may be discovered by men of — 
* Annales de Chimie et de Physique, Jupe and July 1817. 
P 4 science, 
