METEORIC STONES. 193 
tation, with charcoal powder, in a peculiar kind of fur- 
nace. The iron produced in Sweden is considered su- 
perior to that of any other country in Europe for the 
manufacture of steel. 
All kinds of edge tools, where excellence is required, 
are made of steel ; and a steel instrument may be imme- 
diately known from an iron one, by letting fall upon it a 
drop of nitric acid or aqua fortis (206), somewhat di- 
luted with water. Lf it be steel, this will occasion a 
black spot ; but if it be iron, it will not have this effect. 
Steel is attracted by the magnet, and is capable of re- 
ceiving a permanent magnetic property, which has led to 
the discovery of the' mariner's compass. Had iron been 
productive of no other advantages to mankind than this, 
it would on this account alone have been entitled to 
their greatest attention, 
Iron, when exposed to the moisture of the atmo- 
sphere, becomes gradually covered with a brown, or 
yellowish substance, known by the name of rust, which, 
if suffered to continue without interruption, will corrode 
the entire substance of the iron. The rust or oxide of 
iron (21) is a substance in considerable request by ca- 
lico printers for a dye. Iron-moulds are spots on linen, 
occasioned by its exposure to iron in damp situations ; 
these are removeable only by the application of an acid. 
There are various modes of preserving iron and steel 
from rust. The following is recommended by an 
eminent French chemist as one of the best. Mix copal 
varnish, made greasy with oil, with about four-fifths of 
the best spirit of turpentine. Apply this by means of 
a sponge, over the whole surface, and allow it to dry. 
This varnish may be successfully used for all the metals; 
and particularly for the preservation of such philosophi- 
cal instruments as, by being brought into contact with 
water, are liable to lose their splendour, and become 
tarnished. 
234. METEORIC STONES are a species of iron ore, 
which have at different tunes been known to fall from the atmo- 
sphere* 
VOL. I. K 
