1875.] Metallurgy. 549 
yielding 350 tons weekly, there appeared to be absolutely no advantage in 
employing calcined instead of raw limestone. It appears, however, that in 
none of the trials was more than about one-half of the carbonic anhydride 
expelled from the stone. 
Some improvements in the form of moulds for casting ingots of steel have 
been effected by Mr. W. Hackney, who explained to the Institute the construc- 
tion of these moulds. Being subject to very sudden and violent alternations of 
temperature, the ordinary moulds frequently crack; but in Mr. Hackney’s de- 
sign the thickness of metal at different parts of the circumference of the mould 
is so adjusted that the expansion when heated is pretty equal all round, and 
the cracking is thus to a large extent prevented. 
An improved form of hearth lately put in at one of the blast-furnaces of the 
Tees Iron Works was described to the Institute by Mr. Charles Wood, whose 
methods of utilising slag are now well known. Mr. Wood’s hearth combines 
the closed-hearth system with an open fore-part, and a new water-plate ar- 
rangement over which the slag is drawn, and by which it is prevented from 
destroying the brick work or fire-clay through which it issues. 
Price’s Patent Retort Furnace, which was brought before the Institute by Mr. 
Lowthian Bell, is an arrangement for avoiding the loss of heat which occurs in 
the gas-producers of the regenerative furnace. Several of these retort fur- 
naces have for some time been in use at Woo!wich. 
Certain improvements in rotatory puddling-furnaces have recently been 
effected by Messrs. E. A. and J. A. Jones, of Middlesbro’. The improvements 
relate chiefly to the means of admitting and expelling water from the casing of 
the furnace. 
Some experiments on puddling by the aid of a blast have been made at the 
Bull Bridge Iron Works, near Wolverhampton, and appear to be of some im- 
portance. The blast is injected through four tuyéres at the top of the furnace, 
and by impinging on the flame, as soon as it has come over the fire-bridge, pro- 
duces an intense heat, which hastens the puddling and is said to improve the 
character of the metal. 
In blowing out a blast-furnace in the Middlesbro’ distri@ some crystalline 
products were found in the upper part of the “ dead horse,” and these have been 
analysed by Mr. G. Johnston, of Leeds, who has communicated the analyses to 
the ‘Chemical News.” The mass of slag and metal under the hearth had 
probably been exposed for 10 or 12 years to a temperature not much below the 
melting-point of cast-iron. The crystals found in this mass are octahedral in 
form, and may be resolved into two portions, one part being malleable and the 
other easily pulverised. A sample of the latter yielded as much as 29°58 per 
cent of graphitic carbon. 
M. Boussingault’s ‘‘ Etudes sur la transformation du fer en acier par la 
Cementation ” will be found in a recent number of the ‘‘ Annales de Chimie.” 
The objects of his experiments were to determine how long the iron and car- 
bon are in contact at a red heat during the process of cementation; what is 
the temperature of the interior of the chests at different stages of the process; 
and what the nature and quantity of the substances acquired or lost during the 
changes effected by cementation. 
It seems likely that metallurgists may soon be able to use petroleum as a 
fuel, if reliance can be placed on what has been called ‘‘ A New System of Oil 
Metallurgy.” Experiments made in New Jersey by Dr. Eames have shown, it 
is said, that petroleum may advantageously be used in the re-heating furnace 
foriron. The petroleum in the Eames furnace is converted into vapour in the 
** senerator,”’ where it drips from shelf to shelf, and during its flow meets a 
slow opposing current of steam. The mixed vapours pass into a chamber 
where they are brought in conta& with a blast of air, and combustion conse- 
quently effected. 
The metallurgist, not less than the physicist, is interested in Mr. W. C. 
Roberts’s recent researches on certain alloys of silver and copper which have 
been brought before the Royal Society. These silver-copper alloys possess 
