METALLURGY. 



529 



ly satisfactory to warrant the construction of a 

 larger concern at Pittsburg by the Siemens- 

 Anderson Steel Company. The rotator plant 

 of this establishment consists of four vessels 

 measuring 11 feet 4 inches in diameter and 12 

 feet in length inside the shell, lined with Wood- 

 land fire-brick four and a half inches thick. 

 The entire charge of ore, limestone, and reduc- 

 ing coal, is introduced at once. The vessel is 

 slowly rotated at the rate of one revolution in 

 every fifteen or eighteen minutes. In about 

 four hours the. slag begins to form ; and, when 

 it becomes perfectly liquid, it is tapped off. 

 The flow of slag continues until the completion 

 of the heat and the drawing of the balls. The 

 yield of iron with fair grades of hematite ores, 

 in December, 1881, ranged from 34-3 to 47 per 

 cent. Several charges with Lake Superior and 

 Tyrone ore have yielded more than 50 per 

 cent ; and Mr. George W. Maynard, of New 

 York, who has given an account of the enter- 

 prise before the American Institute of Mining 

 Engineers, expresses no doubt that an average 

 yield of 50 per cent can be kept up with this 

 mixture. The average time for forty-eight 

 heats, "through good and bad," from the 

 charging of the ore to the drawing and shin- 

 gling of the balls, was a little more than nine 

 hours, and it was anticipated that with more 

 experience the time would be reduced to eight 

 hours, or three charges in twenty-four hours, 

 with a product of 15 tons of blooms. The cost 

 of 38 tons of hammered steel blooms produced 

 during the week ending December, 1881, was 

 $30.15 a ton; with regular working, however, 

 90 tons might have been produced at an esti- 

 mated cost of $25.24 a ton. The blooms have 

 proved to be of excellent quality, and the steel 

 made with them upon the open hearth is supe- 

 rior to that made with scrap-iron or scrap- 

 steel. The cost of making open-hearth spring 

 steel from the blooms is estimated by Mr. May- 

 nard to be $37.18 a ton. The results so far 

 obtained at Tyrone and Pittsburg, though very 

 encouraging, are far short of what Dr. Siemens 

 has set out to accomplish. That mark has, 

 however, been reached at the works in Lan- 

 dore and Towcester, England, where from one 

 ton of small Somorrostro ore and twelve hun- 

 dred-weight of hammer or roll scale, with one 

 ton of producer coal and six hundred-weight 

 reducer coal, has been produced one ton of 

 iron, at a cost of 1 12*. 9d. 



In the Bromfield direct process of Mr. J. 

 Coley-Bromfield, Hone, near Brighton, Eng- 

 land, the iron-ore and coal, or coal-dust, are 

 reduced to a powder by means of a Mars- 

 den or a Western pulverizer. The pulveriza- 

 tion of the ore maybe facilitated by previously 

 calcining it. For this purpose it is roasted in 

 grated ovens above a tank filled with water. 

 The roasted ore can pass directly from the 

 ovens into the water in the tank, when it be- 

 comes so disintegrated and friable that the re- 

 duction can afterward be accomplished at an 

 expense almost nominal. The crushed iron-ore 

 VOL. xxn. 34 A 



and coal-dust are then mixed, and to them is 

 added carbonate of lime, also powdered, ready 

 for mixing, alumina and sand, after which the 

 materials are passed through a mixing-machine. 

 The compound produced by the mixer is then 

 made plastic by adding a mucilage extracted 

 from steamed sea-weed, which cements it to- 

 gether, and it is then molded and compressed 

 in a kind of brick-making machine. The com- 

 pressed materials, in the form of bricks or cyl- 

 inders, are then removed to a retort, when 

 they are consolidated into coke by a process 

 similar to that for gas-making, but with a spe- 

 cially constructed furnace. Carbonate of lime 

 or calcium oxide is added to the fire-clay in 

 the upper part of the retort, to absorb the sul- 

 phur given off from the ore during the process 

 of distillation. As the materials have been 

 powdered and intimately mixed so as to be 

 brought within the close grasp of their several 

 chemical affinities, a great saving of fuel is ef- 

 fected and the output of the furnace is largely 

 increased. Mr. Bromfield expresses confidence 

 that the adoption of his process in the old 

 blast-furnaces will be attended by several sal- 

 utary results, among which are an increase of 

 30 per cent in the weekly produce of iron ; 

 the invariable production of a pig wholly free 

 from injurious impurity and yielding malleable 

 metal of the largest fiber, no matter how much 

 sulphur may originally have existed in both 

 the fuel and the ore ; a very large saving in the 

 average quantity of fuel now required for the 

 smelting of each ton of pig; and the realiza- 

 tion of all these advantages at a cost so small 

 as to be hardly worthy of consideration when 

 viewed in connection with the additional net 

 profit. Another advantage is claimed in the 

 high commercial value of the results to be ob- 

 tained by economizing and utilizing the prod- 

 ucts contained in the materials placed in the 

 retorts, but which under the present usage are 

 allowed to escape into waste. It is believed 

 that these products will alone repay the cost of 

 preparing the iron-ore for the smelting-fur- 

 naces. 



APPLICATIONS OF MANGANESE BRONZE. 

 Great improvements are promised in the con- 

 struction of steamship-propellers from the 

 adoption of manganese bronze. A theoreti- 

 cally perfect propeller should have blades pre- 

 senting the requisite surface of the right form 

 to act against the water so as to utilize the 

 whole power of the engines in the line of the 

 vessel's keel, while no resistance should be ex- 

 cited from cleaving the water. These condi- 

 tions can not be realized, because there is a 

 limit to the extent to which the thickness of 

 the blade can be reduced, and it is impossible 

 to do away with surface-friction ; but a nearer 

 approach can be made to them with the use of 

 the substance just named than with any other 

 material that has been suggested for the pur- 

 pose. Manganese bronze has great strength 

 and toughness, its transverse strength being 

 double that of the best gun-metal, and up to- 



