436 NOTICES OF THE MEETINGS [May 5, 
found in egg-shaped masses of various sizes ; and on carefully splitting 
these in a longitudinal direction, it is not unusual to find in the 
centre, as a sort of nucleus round which the carbonates of iron and 
lime and of clay have arranged themselves, a shell or a vegetable 
remain. [One of these in a great state of perfection, from the Cwm 
Celyn Iron-works in South Wales, was on the table. ] 
The Oolitic Ironstones of Northamptonshire are also beginning to 
excite considerable attention. They are found, in largest quantity 
and best quality, along the Northampton and Peterborough line from 
Higham Ferrers to Hardingstone near Northampton; and from 
Gayton near Blisworth to Towcester. They are of very varied 
character, and the per centage of iron which they contain ranges from 
20 to 55 per cent. 
Treatment of the Coal measure Ironstone.—The ore occurs in beds of 
varying thickness and generally inclined to the horizon. There are 
usually several beds or seams one beneath another, separated by beds 
of other minerals, and in all such cases every bed has a local name, 
frequently of a very fanciful nature, applied to it. The ore is stacked 
and exposed for some months to the weather, during which time the 
outer coating, containing but a small quantity of iron, cracks and falls 
off. The first process that it undergoes is that of roasting, which is 
performed either in the open air or in kilns, the latter being most 
effectual; by this process it loses water and carbonic acid, the loss 
of weight being about 25 per cent.; and the iron from being in the 
state of carbonate, is brought into the state of peroxide, and is now in 
the form of a red, more or less porous mass, a state in which it can 
be acted upon more readily in the furnace. By roasting, the ore also 
loses the sulphur, though the ironstones of Cwm Celyn, to which the 
Lecturer’s attention has been more particularly directed, contain very 
small quantities of that pernicious element. 
The amount of carbonate of iron in the coal measure ironstones, 
varies from 50 to 80 per cent.—the other constituents being silica, 
alumina, lime, and magnesia, with minute quantities of sulphur, 
phosphorus, and potash. 
The Blast-furnace was next described. The outer stack is com- 
posed of stone or brick, within which is a casing of masonry about 
fourteen inches thick, which when the furnace requires to be re- 
newed inside, admits of being taken down and rebuilt without injury 
to the outer fabric; next comes a space of about six inches filled 
with river sand compactly rammed in,—which being a bad conductor 
of heat tends to preserve the casing of masonry; lastly, a coating of 
best fire brick about fourteen inches in thickness. 
The following are the names and dimensions of the internal parts 
of the furnace. Ist, The hearth, which may be from three to six 
feetin width. 2nd, The boshes,—height from twelve to sixteen feet ; 
width from twelve to fifteen feet. 3rd, The cone or cavity, height from 
thirty to thirty-six feet ; total height of the furnace from forty-five to 
fifty feet. The furnace when in full work contains upwards of one 
