IRO 
prepares his cotton yarn by boiling it five 
hours in a mixture of water made grass 
green with sheep’s dung and a solution of 
white soap ; twice more, an hour each time, 
with half the quantity of soap ; and a fourth 
time in a ley of pot or pearl-ashes, one 
pound to twenty of yarn, another hour. He 
then passes it through iron liquor, to every 
gallon of which half a pound of red chalk, 
or ruddle, in powder, is added ; the liquor 
being poured off clear, after it has stood 
four hours to settle ; and immerses it in an 
alkaline lixivium. AFhen of the proper co- 
lour, for which this operation may be re- 
peated if necessary, he dries it, as after 
each of the former processes ; and then 
puts it into a warm lixivium, in which it is 
brought to a scald. It is afterward to be 
soaked an hour in water made almost as sour 
as lemon juice with sulphuric acid, and then 
washed and wrung twice. Lastly, it is to 
be boiled slowly an hour in a solution of 
white soap, one pound to ten of yarn. 
. The ancients appear to have had the art 
of preparing a blue enamel from iron. M. 
Klaproth analysed a piece of antique glass 
of a sapphire blue colour, transparent only 
on the edges, two hundred grains of which 
gave the following products : silex 163 
grains ; oxide of iron 19 ; alumina 3 ; oxide 
of copper l ; lime 0.5. The loss was 13.5. 
Iron is veiy liable to be oxided, or con- 
tract rust. Conte informs us, that if fat oil 
varnish be mixed with half, or at most four- 
fifths of its weight of oil of turpentine, and 
this be applied lightly and evenly with a 
sponge to iron or steel, and left to dry w here 
it is not exposed to dust, the metal will re- 
tain its lustre, without any danger of rust- 
ing. In order to prevent gun-barrels from 
rusting they are frequently browned. This 
is done by rubbing it over, when finished, 
with aquafortis, or spirit of salt diluted with 
water, and laying it by for a week or two 
till a complete coat of rust is formed. A 
little oil is then applied, and the surface, 
being rubbed dry, is polished by means of 
a hard brush and a little bees-wax. 
The yellow spots, called iron moulds, 
which are frequently occasioned by washing 
ink spots with soap, may in general be remov- 
ed by lemon juice, or the oxalic or tartarous 
acids ; or by muriatic acid diluted with five 01- 
six parts of water, but this must be washed off 
in a minute or two. Ink spots may readily 
be removed by the same means. If the iron 
mould have remained so long, that the iron 
is very highly oxided, so as to be insoluble 
in the acid, a solution of an alkaline sulphu- 
IRO 
ret may be applied, and, after this has been 
well washed off, the acid will remove the stain. 
IRON-FOUNDRY, the art of casting 
iron, and forming moulds, into which it is 
poured when in a fluid state. 
The moulds are commonly made in sand, 
held in wooden frames, (fig. 3 and 4, Plate 
Iron-foundry.) Two of these frames, A B, 
(fig. 4.) are called a .pair of flasks, and fit 
together by pins, a a, in one flask, entering 
eyes, b b, in the other. A wooden pattern 
of whatever is to be cast must first be made, 
exactly of the same dimensions as the article 
1 equir ed. For an example, we have chosen 
to describe the manner of casting a roller, 
such as is used for the wheels of small wag* 
gons, the rolls of windmill heads, &c. Thf 
pattern is shown in fig. 5, 6, and 7 : fig. 5 if 
a plan, fig. 6 a section, and in fig. 7 it is 
shewn edgeways. Thk pattern is exactly 
similar to the wheel which is to be cast ex- 
cept that in place of the hole through the 
centre of the wheel : a pin, m, is stuck on, 
projecting from each side in the same place 
that the holes will be : the use of these pins 
will be shown hereafter. The lower flask, 
A, (fig. 4.) is placed on a board laid on the 
ground : it is then filled with sand, and ram- 
med down, first with the rammer, (fig. 9) 
and afterwards with fig. 10, which is broader, 
and smooths the work. The workman then 
with the trowel, (fig. 8) digs out a hole in 
the sand, and presses the pattern into it, the 
flat surface horizontal, and fills the sand in 
round the pattern, until it is exactly half bu- 
ried, he then takes out the pattern, and if 
there are any holes in the under part, where 
the sand is not filled round close to the pat- 
tern, he puts in a small quantity of sand, and 
presses the pattern down again, until a per- 
fect impression of it is left in the sand, as in 
fig. 1. He nowreturns the pattern, and sprin- 
kles some dry sand, which has been burnt in 
the furnace, over the pattern and flask, and 
then places the upper flask, B, (fig. 4) upon 
it : two small sticks are placed upon the pat- 
tern, and the sand filled in round them ; the 
sand is rammed down by the rammers (fig. 
9 and 10), and the two sticks drawn out, 
leaving holes, 1 1, (fig. g) through the sand 
in the upper flask. The workman now 
takes oflf the upper flask, B, by its two 
handles, leaving the pattern in the lower 
flask ; the burnt sand causes the two flasks 
to separate exactly at the joining of the 
flasks : the upper flask is now completely 
finished, the holes, 1 1, made by drawing out 
the sticks, being left to pour in the metal, 
and the pattern leaving a perfect print of 
