The Sun.
London, England, 1837-09-19 00:00:00

specific gravity of 3,380-; but the richest ore in that

neighbourhood was 3,056. The lightest specimen of
iron stone he had met with was 2,285, and contained •
no more than thirty-nine per cent. of iron. Before the
ore is put into the furnace, it is always roasted to drive off
the carbonic acid, which reduced it thirty-five per cent.
Lime was then introduced with it in the furnace as a fluid.

The purest limestone used contained 241 per cent. of cal-
ceums. The coal used for fuel gave 10 per cent. of ashes.
_ .

Coal was seldom quite free from pyrites, which accounted
for the quantities of sulphur formed in cast iron. When iron
was smelted in former times, 10 tons of coal were required
fur the reduction of one ton of iron. In 1823, when the

!node of heating the air was brought into operation, and
blasts sufficiently hot to melt lead were introduced into the.
furnace, two tons 19 cwt. were only required for the same

purpose, 19 cwt. of which were consumed in heating the air,
and in heating the boilers of the stPam•cngine used. He
considered that coals were used with more economy in the

lot than in the cold blasts, because, by the cold blast the

heat was carried up the chimney and dispersed, whilst in
the hot the heat was instantaneously communicated to
the ironstone. This greater concentration of combus-
tion ain't melt the iron in a greater degree ; this ac-
counts for the smaller quantity of lime required for
fusing the clay, and thence the greater quantity of cast
iron obtained from a furnace in a given time. The Carron
iron works supplied him with specimens of No. 1 iron, made
from hot and cold furnaces. The Carron Company had the
reputation of making cast iron of very good quality. The
specific gravity of cast iron, smelted by cold hlast, is less
than that smelted by hot blasts. The following- was the

gravity of a number of specimens of No. I cast iron,
smelted by the cold blast, obtained from different furnaces
—.5 from Muirkirk, of the following specific gravity :
6.410-6.435-6.493-6.579-6.775. Pyrites, 6.9944.
From the Csrron foundry, 6.9888. Clyde works, 7.008.
In all tiles., specimens of cast iron other ingredients were
found besides iron. Nothing was more astonishing than the

differences in the quantity of carbon, which existed in va-
riolo proportions even when smelted at the same place.
He hall examined some hot iron, said to have been Swedish,
the specific gravity of which was 7.663, but which, owing
to the presence of sulphur, which did not occur in Swedish,
he did not believe to be such. Mr. Tennant had examined
a .pecimen of cold blast iron, NO. 2, which contained
90i per cent. of iron. He had analysed five specimens of
hot blast iron, two of which were the Carron, and three
nom the Clyde iron works, where the hot blast was first
used, the specific gravity of which were 7 0028-7.0721-
1.1022-1622—while 7.0623 was the mean. From a table
of the constituent parts, it appeared that 95i per cent. was
the average mean of iron by the hot bast. Hot blast iron
is thus obviously purer than cold blast iron.. The manu-
facture of the iron from the hot blast was not so tough as
from the cold blast, but lie did not know what they meant,
as the two descritations of iron took the same force to break
them. The best steel produced at Glasgow, was made by
Mr. Tennant, and found tt.; be constituted as follows :
Iron 99.68 ; Mangaitese o.ll.lo;Carbon 0.335. They
never could get the exact 100 parts by- analysis, andwhere-
everDeadness
they found them, they might be certa;_o it was an ana-
lysis made on paper. He considered that the
the steel was owing to the absence of foreign suth:!anees.
If they used the same quantities of coal with a hot bList
as with a cold blast, they would not get iron at all, they
must only use half the quantity of coal to the hot blast.
smelted
b yTthhoemhsootn
atnhe n
d coldblast, exhibited p
fsroemc i The: sof in Na.
samer iron
ore. The
1,
e
force required to break them was the same, being 2,0401bt.
the iron being 9-Bths thick. He also exhibited a chain
forged of malleable round iron, 7-Bths thick, which had stood
the test of 22 tons 7 cwt., or more than twelve tons above
the Liverpool chain cable test, This iron had been forged
from hot blast iron,
A long conversation ensued on the emnparative merits of
the iron prepared by the hot and col i• blasts,
Dr. TRAIL then read a papa: upon a new compound of
antimony as a pigment which he had discovered last winter,
when adding a solution of ferroprussiate of • potash to
muriate antimony, by which he had produced very beautiM
blue prussiate, somewhat resembling ultramarine.
D. NEIL ocean read a paper on a new safety lamp
for mines. His idea was to supply lamps at fixed stations
in the mines, with air from the surface, hy means of cheap
woven pitched pipes,inte which the air should be injected