100 Progress in Science. (January, 
been increased, and in 1871 furnaces were constructed with a height of 
95 feet 6 inches, a diameter at the bosh of 24 feet, and a capacity of 28,950 cubic 
feet. Indeed, one of the furnaces erected in the previous year held not less 
than 41,149 cubic feet. In the opinion of the author, the useful maximum 
both in height and in diameter have been already attained, if not, indeed, 
exceeded. Within certain limits, showever, increase of size leads to increase 
of make, to economy of fuel, and to improvement in the quality of the pig-iron. 
The author proceeds to give a detailed description of the Ayrsome Iron Works, 
on the River Tees. Two furnaces are already in blast, and two others will 
probably be ready for blowing in the spring. The furnaces are closed by a 
cup-and-cone arrangement, and the waste gases are carried down to an 
underground culvert. Each furnace has a height of 85 feet, and a maximum 
diameter of 25 feet. 
A subje@ somewhat akin to this, but more local in its bearing, was brought 
forward at the same meeting by Mr. T. W. Plum, in his paper ‘On 
Increasing the Height of Blast-Furnaces in the Midland Distri@s.” The four 
Old Park furnaces, built half a century ago, were each 45 feet high; but a new 
furnace, 60 feet high, has recently been erected in place of one of these old 
forms, whilst an additional height of 15 feet has been given to another of the 
furnaces by carrying up a casing outside the former tunnel-head. Hence 
there are now two 6o-feet furnaces and two 45-feet furnaces working side by 
side. At the time the paper was read, but little experience had been ob- 
tained respecting the comparative merits of the two forms of furnace; but 
even from the results then in possession of the author, he felt justified in con- 
cluding that a considerably increased yield had been effected by the increased 
height, and that in districts where tender cokes were used a height of 60 feet 
might, under existing conditions, be safely attained, but not perhaps 
exceeded. 
From some recent experiments on the evolution and appropriation of heat 
in blast-furnaces where raw coal is employed, Mr. I. Lowthian Bell is led to 
conclude that in the Ferrie self-coking blast-furnace, which has been worked 
with very economical results, one-half of the saving of fuel may be referred to 
the increased height of this furnace, and the other half to the combustion of 
the inflammable gases in the flues constructed in the upper part of this form of 
furnace. 
Mr. Barclay, of Kilmarnock, has proposed certain improvements in the 
construction of blast-furnaces, whereby a considerable saving of fuel is said to 
be effe@ed. An annular flue, concentric with the shaft, is constructed in the 
masonry near the top of the furnace; and a portion of the gases escaping 
from the upper part of the charge gains access to this flue by a series of 
radiating passages. A number of vertical pipes arranged around the furnace 
serve to convey these gases downwards to a lower level, where they enter 
another annular flue; and, becoming ignited by contact with jets of atmo- 
spheric air, again enter the furnace. The heat evolved by the combustion is 
thus imparted to the materials of the charge, while the admission of air 
is so regulated that no oxidising action is exerted upon the contents of the 
furnace. 
Some valuable researches on the composition of the gases evolved from the 
Bessemer converter during the blow have been undertaken by Mr. Snelus, of 
the Dowlais Iron Works. Analyses were made of the gases given off at 
different periods of a blow lasting eighteen minutes, and the author thus seeks 
to gain some insight into the nature of the process which goes on within the 
converter. The analyses are presented in a tabular form,* and show the 
relative proportions of carbon and silicon which are successively eliminated at 
different stages of the operation. 
* See Chemical News, O¢t. 6, 1871, p. 159. 
