of its weight in gas, or three per cent. of its volume. The condensing apparatus consists of 3,500 pounds of iron bars piled crosswise on each other, and kept cold by a jet of water from a tuyere. The heat of the gas before condensation of the water always melts lead easily, and sometimes zinc. The expense of the construction of a full-sized furnace in Sweden is about $2,500 in currency, and it is estimated that such a furnace will utilize 1,700 tons of fuel in a year, at a saving proportioned to the cost of other fuel in the particular locality where it is employed. In Sweden it is estimated that the annual saving, resulting not merely from the cost of the fuel, but from the repairs of the furnace and the increased temperature, amounts to over $5,000 per annum on the product of each furnace. In the Ekman furnace dry wood containing eight per . cent. of water produces in the generators gas of a temperature of 1,3940, while in the Lundin furnace the temperature is 2,666°, the combustion in both cases being produced by cold air. The gas produced by seasoned wood contains more water than that which proceeds from the Lundin condenser. The duration of the furnace is simply surprising, and is to be attributed probably to the fact that there is no cinder. In eight weeks the thickness of the roof, 4 inches, was only diminished from to inch, and the side walls were entirely uninjured. So wonderful is the success of this system of condensation, in connection with the Siemens' regenerators, that, in Sweden, and in fact everywhere where moist fuel is employed, the Lundin furnace will supersede every other. Its great merit is, that it is available for any kind of fuel whatever. In the United States it is believed that this arrangement might be employed advantageously for washing the gas obtained from mineral coal; but its chief merit consists in the fact that in mineral regions, far removed from the coal fields, it is possible to establish iron works, using sawdust or peat with entire success and great economy. In the lumber regions of Lake Superior it will be found to have a special value, because there is an abundant supply of pig accessible to the saw-mills on Green Bay and in Michigan, producing enormous quantities of sawdust, slabs, and waste timber.

Although reluctantly I have been compelled to abandon the idea of accompanying this report with drawings, and to rely rather on references to printed publications, the drawings of the Lundin furnance are annexed in Appendix B, not merely because they are not elsewhere attainable, but because the value of the invention is such as to secure its immediate introduction into the United States, in many parts of the country where mineral coal is dear or not attainable.

The Exposition presented very complete specimens of pig iron from all parts of Europe, but the experience valuable to our American ironmasters could only be acquired by actual visits to the works where they were produced. In South Wales the most remarkable feature was the endurance of the furnaces, some of which had been in blast for more than 20 years, and no furnaces were expected to go out of blast under 10 or 12

years. As the production of these furnaces varies from 200 to 300 tons per week, and the ores and coal are not less calculated to wear the lining than our own, it would be very desirable to determine the cause of this greater durability. In Wales the heat of the blast is usually about 600°, and its pressure from three to three and a half pounds per square inch. As all these conditions are to be found at particular works in the United States, where furnaces continue in blast only from three to four years, it would seem that the quality of the bricks might explain the difference. Another peculiarity of South Wales is the great difference in the product of furnaces having the same dimensions and shape and using the same materials, and for which the experience of the iron-masters offered no adequate explanation. Again, at Ebbw Vale, the Sirhowy furnace, 73 feet in height, 18 feet across the boshes, with the hearth seven feet six inches in diameter, and the tunnel head ten feet in diameter, containing 11,900 cubic feet, did not produce as much iron as another furnace seventeen feet six inches across the boshes, forty-eight feet high, with the same sized hearth and top containing 6,590 cubic feet. This latter furnace averaged about 380 tons of iron per week, using about one and a half ton of raw coal to the ton of iron. Its interior section was in the form of two cones meeting at the boshes, and a drawing of it will be found among the Ebbw Vale furnaces, marked E. V., No. 3, p. 559 of Percy's Metallurgy of Iron and Steel. The only mechanical arıiangement of these furnaces worthy of special notice is the cup and cone device at the tunnel head, which is described in Percy, page 470, perfected at the Ebbw Vale iron works, and now generally adopted at all the large iron works in Great Britain and on the continent, except in Scotland and in the Cumberland region, where it is supposed to have an unfavorable influence on the quality of the iron. The object of this arrangement is to throw the small ore and coal against the sides of the furnace, and the large pieces to the centre, and it was stated to be essential that the cone when drawn up to its place should have a space of 18 inches between it and the lining of the furnace. From the space thus produced the gas is drawn off for the supply of the hot blast ovens and the boilers, which, in the great majority of cases, were placed upon the ground and not upon piers, and no difficulty is experienced in procuring an adequate supply of gas below by the draught of high chimneys. It was generally stated that the adoption of the cup and cone arrangement had improved the running of the furnaces and diminished the consump tion of coal.

The Cumberland region has long been remarkable for the large product of iron from its blast furnaces. Even as early as 1862 a weekly product of over 600 tons had been achieved in one furnace, and although the business has greatly extended in that region, and is still characterized by large weekly products, it does not appear that any improvements have been lately made either in construction or in yield. At Barrow-in-Furness there are six furnaces 15 feet across the boshes, by 42 feet high; and five

furnaces of 173 feet across the boshes, and 47 feet high. When working for pig iron designed for the Bessemer process, the smaller furnaces make 300 and the larger 400 tons per week of extra gray pig iron, but this product is very largely increased when the furnaces are running on forge iron, a single furnace having made as much as 700 tons in a week. This remarkable product is due to the admirable character of the ore, which is a red hematite, yielding 60 per cent. on the average, and is smelted with a ton of coke per ton of iron, but when the grayest iron is made the consumption of fuel is undoubtedly greater. Admirable as these works are in construction, and producing annually the enormous quantity of 200,000 tons, there was nothing in the process of manufacture calling for special notice.

But at no point in Europe was the lesson of the superior advantage of good quality more plainly inculcated, for here, on the west coast of England, gray hematite iron was selling for 90 shillings a ton, while on the east coast of England gray Cleveland iron could be purchased for 40 shillings per ton; the one finding a market in the Bessemer process, where only the very best iron can be used, while the other had to be sold in competition with the great mass of inferior pig. But though the iron of the Cleveland region be inferior, it is there that the American ironmaster has most to learn. The ore of the Cleveland region is of the fossiliferous variety, yielding 31 per cent. raw, and 42 to 43 per cent. when roasted. The coke is extremely tenacious, enduring a heavy pressure without being crushed. The first furnaces built were about 18 feet in diameter and 55 feet high, making a weekly product of about 230 tons, with a consumption of 11⁄2 ton of coke to the ton of iron, and a temperature of blast of from 600° to 700°. The excellent performance of the stock in the furnace soon led to an increase in its height, with a corresponding increase in the temperature of the blast, and now there are furnaces in operation in the Cleveland district 102 feet in height, 27 feet across the boshes, and driven with a blast of a temperature of from 1,000° to 1,1000, or at least sufficient to melt pure zinc, back of the tuyeres, in from four to five seconds. The consequence is that the consumption of fuel has been reduced to a ton of coke to the ton of iron, and there has been a gain of two per cent. in the yield of the ore, which latter phenomenon is attributed to the use of the Player stoves for heating the blast. In this arrangement the gas is burned in a separate chamber, and only the resulting heat reaches the pipes. Thus all floculent matter is disposed of and the pipes require no cleaning, and their liability to injury is far less than when the flames come in contact with the pipes, subjecting them to the danger of being burned in spots. The pressure of blast is from 3 to 4 pounds to the inch, and six tuyeres of 3 inches diameter usually serve to convey it to the furnace. At the Norton works, where there is a furnace 85 feet high by 25 feet boshes, there were four stoves, containing 60 pipes weighing 126 tons, which heated the blast from a blowing cylinder of 7 feet by 7 feet, making 13 revolutions per minute. The general rule

for blast is that there shall be 1,200 square feet of heating surface for each 1,000 cubic feet per minute.

The effect of this change in the size of the furnace and the heat of the blast in the Norton furnace above referred to was to give a weekly product of 365 tons. All these furnaces have the cup and cone arrangement at the tunnel-head, and the gas is drawn off into a great iron flue forming a kind of cornice or moulding around the top of the furnace, but covered with brick so as to avoid radiation. A proper outlet for the gas is indispensable for the larger product and economical results which have been described. The pipe for conducting the gas to the ground must not be less than 7 feet in diameter, and is lined on the inside with brick.

All the ore of the Cleveland region is calcined in vertical kilns, varying from 24 to 35 feet in height, and from 4,500 to 8,000 cubic feet capacity, charged with ore and fine coal in layers, and consuming about one ton of coal to 24 tons of ore. This calcining might be far better done by the Westman furnace, but unhappily the supply of gas from the blast furnace is not more than sufficient to heat the boiler and stoves. All the usual modes of elevating material to the top of the furnace are to be found in this region, but the pneumatic lift more recently introduced merits attention, as working in a very satisfactory manner. It consists of a cast-iron cylinder of the height of the furnace, made in sections bored out and bolted together, so as to provide a chamber 36 inches in diameter, in which the piston fits loosely, and weighs about half a ton more than the platform and empty barrows. Leather packing is used to render it airtight. The platform surrounds the cylinder, and is put in motion by the movement of the piston, with which it is connected by wire ropes passing over four eight-foot pulleys at the top of the cylinders. Four barrows of material are raised at a time, weighing from one to two tons, and the upward and downward motion is communicated by the alternate exhaustion and compression of air beneath the piston to the amount of from one to three pounds per square inch, according to the load. A pressure of one pound to the square inch is required to lower the empty barrows. For the calcining kilns, a similar arrangement, but of greater power, is employed.

The early introduction of the high furnaces into the United States would seem to be inevitable, provided the fuel is strong enough to resist the pressure which is involved. Our magnetic, carbonaceous, fossiliferous, and red hematite ores, except in a few instances, are remarkably well adapted to these furnaces, and if it should be found that our admi rable anthracite will not decrepitate when subjected to the incidental pressure, it is not hazarding much to predict that the consumption of fuel can be readily reduced to a ton for each ton of iron made.

An analysis of the coke used is subjoined, as a guide to those who employ that fuel:

Carbon....

Volatile hydro-carbons.

91.42

0.64

Sulphur

Ash..

Moisture...

1.

6.66

0.28

Among the other curiosities connected with the Cleveland iron, is an analysis of the dust which is deposited by the gas in its passage from the furnace through the stoves and under the boilers.

So large a proportion of zinc from an ore which contains no zine is a phenomenon not unobserved at other places, but has as yet received no satisfactory explanation.

The Player stove was the subject of commendation in the Cleveland region, and appeared to be as satisfactory a mode of heating the blast as any in use. But it is proper to say that an equally high temperature can be procured in other ways.1 The introduction of a hotter blast into the United States will certainly effect a large saving of fuel, but the effect upon the quality of the iron must in a great measure depend upon the character of the ores employed. Its combination, however, with the high furnaces certainly affords one of the most interesting and instructive lessons in recent metallurgic improvements.

In Scotland, where for so long a time the yield of blast furnaces was in advance of all other regions, no progress seems to have been made, the furnaces rarely exceeding 200 tons per week. An attempt has indeed been made at Gartsherrie to increase this amount by the erection of two furnaces 60 feet in height, but the consumption of fuel has not been reduced, and the yield of the furnace in iron not materially increased. This is noted here in order to suggest caution in our own progress toward higher furnaces, because the increase in the height of the furnace at Gartsherrie appears to have increased the quantity of solid matter

66 Man

Stoves made with fire-brick, under Cowper's patent, or modifications thereof, are found to work well, and are growing in favor. They are described in Bauerman's admirable nal of Metallurgy" republished by Van Nostrand in New York.