230 Society for the Encouragement of 
The employment of iron in a malleable state or converted into 
steel, in machines which are not regularly worked, occasions a 
rust which renders them frequently unfit for use after a lapse of 
time, sometimes very short, according to the nature of the iron _ 
or the vicinity of marine vapours. This effect is chiefly felt in 
the case of machines for mashing fruit and cutting esculent roots. 
However, these instruments are daily multiplying throughout the 
country, and it is much to be feared that the rust which affects 
the quality of the substances on which they are employed, at the 
same time that it destroys the instruments themselves, may bring 
them into general disrepute, the result of which would be ruin- 
ous to the pregress of agriculture and the arts. 
The Society of Encouragement invite men of science and 
artists to remedy this imperfection, either by employing pro- 
cesses already known or to be yet discovered for preserving iron 
and steel, or by substituting in their place other metallic sub- 
stances. 
Among the metals which may be so employed, it may perhaps 
excite surprise tu find platina mentioned. It is to be regretted 
that this metal, invaluable for such a purpose from its firmness 
and unalterability, should be so very dear ; but there is reason to 
hope that ere long it will become more common, and it is not 
mpossible that it may then be employed with ceconomy, at least 
for the exposed parts. Besides, instead of subjecting it to long 
and expensive operations in order to render it malleable, may it 
not be employed when less pure and ductile, by taking it in a 
crude state, suchas it is found in commerce, and uniting it with 
other metals which it may protect from oxidation ? Itis certain 
that tin can greatly increase its fusibility, and produce combi- 
nations perhaps less malleable but yet harder than iron, sound, 
and sensibly less liable to oxidation. As much may be said of | 
iron united to tin and platinum; and there is reason to hope that 
these compounds, already from five to six times at least more 
marketable than malleable platinum, may be very usefully em- 
ployed. The very hard compound of copper, tin and platinum, 
employed by M. Rochon in the manufacture of telescopes, has 
been long known. 
The other metals which combine chemically—the binary, ter- 
nary, quaternary compounds, &c. may they not in varied pro- 
portions afford favourable results, which have not hitherto been 
obtained, only because they have not been examined? Let us 
instance a few combinations. - 
A mixture of tin with iron, without any portion of copper, pro- 
duces a hard, innocent, malleable, and very resisting compound, 
which is by no means made use of to the extent it might bee 
whic 
