METALLURGY. 



537 



in the usual way, and is then molded in con- 

 junction with the pattern; when the latter is 

 removed, the core is allowed to remain in the 

 flask, and the melted iron is poured over it. 

 The iron is prepared by a flux for ready amal- 

 gamation with the brass ; and when the com- 

 pound casting is taken from the sand, it is found 

 to be a complete and well-connected piece, with 

 the two metals in perfect union. When it is 

 desired to separate the two metals, the brass 

 is melted at a lower temperature than the melt- 

 ing-point of iron, and is then run out from its 

 backing. 



Mr. A. D. Elbers is the inventor of a process 

 for the conversion of mineral wool into silicates 

 previously desulphurized, to be used in the 

 manufacture of china-cement, pigments, and 

 absorbents. The suitable raw material for his 

 purpose is uni-silicate or neutral slag, which 

 contains the usual percentage of sulphur in 

 soluble compounds. The first step in the con- 

 version is the reduction of the slag to a finely 

 fibrous condition by subjecting it, while in the 

 fluid state, to jets of steam. While the steam 

 divides the fiery mass into fibers, it also slightly 

 reacts chemically on the sulphur compounds, 

 whereby the fibers become predisposed to 

 further reduction. The second operation is 

 the roasting of the non-fibrous and very volu- 

 minous slag until no further evolution of sul- 

 phurous-acid vapors takes place, whereby the 

 opening of the fibers and the reuniting or fit- 

 ting together of their constituents freed from 

 sulphur is accomplished. The fibrous slag haa 

 been changed to a granular substance of puri- 

 fied composition ; if the heat is increased after 

 the change has taken place, the result will be 

 a fused mass of desulphurized slag; but if too 

 much heat is applied before desulphurization, 

 the libers will be remelted into fused slag of 

 the original composition. The whole product 

 may be reduced to the most desirable condition 

 in which it appears, described as " a mass of 

 whitish, soft silicate, containing some impuri- 

 ties," by a proper regulating of the heat. This 

 desulphurized and easily friable silicate is finely 

 pulverized, and, after being purified by wash- 

 ing, is ready for use in the arts as slag-silicate 

 of alumina, iron, and magnesia. 



Malvern W. lies has found his method for 

 the decomposition of slags for analytical pur- 

 poses by fusing the finely powdered slag with 

 caustic potash in a silver crucible applicable to 

 a large class of ores and furnace products. It 

 is also capable of a wide application for esti- 

 mating sulphur in slags and minerals by such 

 fusions, and the subsequent use of bromine- 

 water. The difficulty arising from the liability 

 of the silver of the crucible to be attacked by 

 alkali, is obviated by using gold-lined or plati- 

 num crucibles. With this modification the 

 method is applicable to the decomposition of 

 nearly all silicates, and to the estimation of 

 sulphur in nearly all inorganic as well as or- 

 ganic bodies. Mr. lies has now found, how- 

 ever, that it is not necessary to make a fusion 



of the slag for purposes of analysis, but that, 

 when the hot-flowing slag is suddenly cooled, 

 it may be completely decomposed by concen- 

 trated hydrochloric acid, and becomes readily 

 attacked by other acids. 



M. F. Gautier has described a new neutral 

 lining for metallurgical purposes, the main con- 

 stituent of which is chrome-iron, a refractory 

 material which, is not acted upon either by 

 acids or bases. 



G. Hatton describes a new type of converter 

 for the production of soft steel, which is claimed 

 to have many advantages over the Bessemer 

 converter. 



A furnace adapted for the consumption of 

 natural gas has been patented by Mr. R. W. 

 Kennedy, of Pittsburg, Pa. The combus- 

 tion-chamber is formed of fire-brick, and is 

 inclosed by an air-chamber. In the combus- 

 tion-chamber is a distributing plate made with 

 a series of notches along the edge, which con- 

 stitute passages for the escape of gas along 

 the sides of the chamber. Directly above the 

 distributing plate a number of openings are 

 formed through, the wall of the chamber that 

 connect with the air-chamber, and run at an 

 angle with the radii of the combustion-cham- 

 ber, so as to impart a swirling or circular 

 movement to the air, which keeps it in con- 

 tact with the gas long enough, to insure a 

 thorough combustion. 



The crucible furnace for steel-melting with 

 natural gas at the Wayne Iron and Steel Works, 

 Pittsburg, is a reversible - draught structure, 

 with regenerative chambers at each side. The 

 main chamber is in six divisions, each of a size 

 to admit six crucibles, making thirty-six pots 

 in heating at once. It is so adjusted that a 

 single pot can be lifted without uncovering 

 the others in the same division. There is 

 nothing in this furnace below the ground-line 

 except the foundation-walls, the regenerative 

 chamber being at the sides. The crucibles 

 used here may be made to yield a service of 

 eight heats by rinsing them, when they begin 

 to get worn, with a semi-fluid wash of plum- 

 bago (old crucibles), silicon (white sand), and 

 kaolin-water. This makes a layer just replac- 

 ing the worn part. 



A machine has been invented for polishing 

 the interior of metal tubes. It consists essen- 

 tially of a strong, trough-shaped iron bed at 

 the end of which is attached mechanism for 

 giving a rotary motion to a long bar which 

 has secured to its outer end cylinders of em- 

 ery ; the pipes are held by means of a sleeve, 

 which is carried along the bed-plate, at the ex- 

 act speed desired, and is so arranged as to re- 

 volve in an opposite direction from that of the 

 bar to which the emery cylinders are attached. 



Mr. F. W. Dick, of Glasgow, has described 

 a new form of furnace, embodying all the 

 principles of the ordinary Siemens furnace, 

 but differing from it somewhat in the con- 

 struction and arrangement of its parts. The 

 furnace and regenerators are separate from 



