1872.] Metallurgy. 99 
there will also be found in them, as usual, much information and many sugges- 
tions which cannot fail to be highly valuable to the practical miner. 
To a recent number of the “ Annales des Mines,” M. A. Henry contributes 
a long paper on the different explosive substances employed in mining. 
In this memoir he discusses at some length the comparative value and the 
conditions of safety in the manufacture, transport, storing, and the use of the 
several explosives which have been introduced as substitutes for gunpowder, 
namely, gun-cotton, nitro-glycerine, dynamite, dualine, and lithofracteur. It 
appears unnecessary to give an analysis of this paper; for, although only 
recently published, it was written upwards of a year ago, and its publication 
delayed by the unhappy state of affairs which interfered with the regular issue 
of most of the scientific journals in France. 
METALLURGY. 
Any mechanical process which may be suggested for superseding the laborious 
work of manual puddling deserves serious consideration. It may be remem- 
bered that. some time ago, Mr. Menelaus, of Dowlais, bestowed considerable 
attention upon mechanical puddling; but after patient and skilful research he 
failed to secure satisfactory results. Mr. Samuel Danks, of Cincinnati, now 
claims to have successfully solved the problem by means of his revolving 
furnace—a furnace which does not, however, appear to materially differ from 
some of those previously devised for the same purpose. The fire-grate is 
supplied with a fan-blast below, and with jets of air from above to ensure 
perfe@ combustion of the fuel; whilst a valve serves to regulate the blast, and 
thus keep the temperature of the furnace under complete control during the 
process. The gases generated by the combustion are conveyed across the 
fire-bridge through a cylinder into the revolving chamber. This chamber rests 
upon rollers, and by means of a toothed wheel may be made to rotate freely. 
The foundation of the lining of the apparatus consists of a mixture of 
pulverised iron ore and lime, mixed with water to a proper consistence. 
Upon this “initial lining,” the fettling proper is applied. At first a certain 
quantity of pulverised ore is introduced and allowed to melt ; lumps of ore are 
then thrown into the molten mass; and, when the liquid has set, fresh 
pulverised ore is introduced; this process being repeated until the fettling is 
sufficiently thick. In the experiments at Dowlais, much of the difficulty con- 
sisted in producing a suitable fettling; but Mr. Danks asserts that any iron 
ore containing not morethan 5 per cent of silica will answer his purpose. The 
pig-iron may be charged in either a solid ora molten state. When the iron is 
melted, the furnace is caused to rotate once or twice per minute during the 
first five or ten minutes of the operation. A stream of water is injected at a 
certain point, and a portion of the cinder is thus solidified; this is carried 
down into the molten iron ina continuous stream. After the temperature has 
been raised, and the cinder run off, the velocity of rotation is increased, the 
charge becomes violently agitated, the mass acquires a pasty consistence, and 
the particles gradually cohere into a ball. During the process some of the 
rich fettling is reduced, so that the puddled produ& adtually exceeds in weight 
the pig-iron introduced. It is said that furnaces of this construction are at 
work with excellent results in several parts of the United States. Reliable 
information respecting the merits of the invention will no doubt be obtained 
by the deputation sent to America for the purpose of examining the process, at 
the instance of the Puddling Committee of the Iron and Steel Institute. 
During the last ten years important alterations have been made in the 
dimensions of the blast-furnaces erected in the Cleveland distri@. This 
subject has been discussed by Mr. John Gjers, at the Dudley meeting of the 
Institute. Although the first blast-'urnace in Cleveland was built in 1851 by 
the late Mr. John Vaughan. there are scarcely any furnaces still in existence 
in that distri& which were erected prior to 1859. The old furnaces were built 
of small size, the earliest having a height of only 42 feet, a diameter at the 
bosh of 15 feet, anda capacity of 4566 cubic feet. Gradually the dimensions have 
