No doubt the presence of foreign subtances, such as carbon and silicon, in the pig iron, means an expenditure of fuel in the blast furnace; but this is not all loss, for these substances serve to reduce so much iron from the ore added, that the actual waste of metal is not one-third of that incurred in the direct process, if both are calculated upon the ore delivered at the very commencement in each case. Of course it may be alleged that in the direct process we have begun with materials containing an amount of phosphorus inadmissible for steel making, and that we have succeeded in separating this substance by avoiding the use of the blast furnace.

Recent experiments however have demonstrated the possibility of washing out almost all the phosphorus contained in cast metal, by means of oxide of iron, so expeditiously and easily, that the cost of doing it would, probably, be attended with much less expense than that connected with the direct mode of reducing the ore.

Practically, the inference to be drawn from what has been advanced in the present Section is, that the removal of the carbon and silicon, absorbed during the ordinary smelting of the ore, is done at so small a cost, as to render it more economical to employ pig iron, than to use the direct process in order to obtain a product free from both of these elements. Now that the Basic treatment has been found so efficacious in separating the phosphorus, it would seem as if the only apparent argument in favour of dispensing with the use of the blast furnace no longer exists.

If the final object in view be not steel but malleable iron, a process which gives us the article we seek in one operation, instead of two, has a most attractive sound; but it is by no means certain that the advantages are not rather apparent than real. Adopting the same classification as before, I am sure that the actual waste of metal accompanying the use of the blast and puddling furnaces will not, including the "fettling" employed by the puddler, amount to that spoken of in connection with the direct process. On the other hand, it seems pretty clear that the payments for labour and fuel will amount to less for the double mode of treatment than they do for the single one.

It is true that in the one case we have as our first result pig iron containing nearly all the phosphorus found in the minerals employed, while in the other we have malleable iron containing less than 1 per

cent. of phosphorus. This same pig, however, containing as much as 1.5 to 1.75 of the objectionable metalloid, can have it separated in the rotatory puddling furnace so completely, as to show an equality in this respect with the analyses mentioned by Professor Tunner.

Having mentioned so high an authority as the learned Professor, I am bound to add that he views the future of these direct processes more hopefully than I have been able to do.

In the work already quoted, Professor Tunner alludes to the fact of the actual production of iron by these processes, 40,000 tons being now the yearly make in the low hearths situate near Lake Champlain, and in other places. I scarcely gather from the context that even here this ancient plan is regarded by him as being able to compete commercially with our present modes of making malleable iron. Without, however, being capable of this, it is easy to understand that an old industry may continue to exist, and even to prosper, in times of high prices and high import duties, notwithstanding that more economical methods may be carried on in its immediate vicinity. This is particularly true of a manufacture requiring such simple appliances as are used on Lake Champlain, and where the product is applied to purposes for which more phosphoric iron is unfit.

ton.

When we come to the matters of cost and waste of iron, I do not apprehend that the figures given by my friend differ in any degree from my own. The ore employed on Lake Champlain is valued at 15s. per It contains 70 per cent. of metallic iron; but only 57 per cent. of rough slabs is obtained at the end of the process, showing a loss of nearly 20 per cent., or above double that involved in puddling pig metal. The particulars of cost of these rough slabs are given as follows:

It may be thought, looking at the wasteful mode of its application, that the quantity of fuel consumed is unexpectedly small, as compared with the combined processes of smelting and puddling. This arises

from the fact that there is little or no earthy matter to fuse, in treating so rich an ore; and also that the temperature required in the low hearth is not so intense as that excited in the blast furnace. As a matter of final cost, however, there are few ironmaking localities where ore valued at 15s. per ton, and containing 70 per cent. of iron, could not be converted into pig iron, and have its phosphorus reduced to 075 per cent., in a rotating furnace, for very much less money than the sum just named. The expectation of substituting mild steel, or ingot iron, for malleable iron made in the ordinary way, has diverted attention from further improvement in the puddling furnace. Nevertheless in that modification of the revolving furnace with which Mr. Samuel Danks' name is associated, a considerable step in advance has recently been made. At Creusôt two such furnaces are at work, in which the shell is kept cool by a current of water; from each of these 8 to 10 tons of puddled blooms are produced every 12 hours, being double the make usually obtained from the furnaces designed by Mr. Danks. The natural effect of this increased output is a considerable diminution in the working expenses, thus rendering it still more difficult for the direct process to compete with the modern art of iron-making.

Tunner states that the Jersey or Champlain system, as this is often called, was the first method practised in America for obtaining the metal; it may, therefore, be concluded that long experience does not permit much hope of its cost being materially lessened. Such is not the case with regard to the other two direct processes more particularly referred to in these pages; and in predicting their future, we are left to apply our general knowledge of the natural properties of the materials dealt with, coupled with such experience as we possess in comparing the expense of a new system with those already in use.

In my short account of the Blair process, given on a former occasion,1 it was stated that the porous sponge, when thrown into the steel furnace, would float on the melted pig iron, and there, to some extent, would be re-oxidized. Mr. Blair at the time dissented from that view, and asserted that the sponge, light as it is, nevertheless sinks; and Professor Tunner himself gives it as his opinion that it is incorrect to suppose that the sponge must be oxidized before it is dissolved by the

1 "Transactions of Iron and Steel Institute, 1875."

bath of metal. From this it is inferred, that sooner or later, we may expect to see Mr. Blair's plan in successful practice-an opinion which, even when backed by the great experience and authority of the learned Professor, I do not see my way to agree with. In support of the incorrectness of my own views, Professor Tunner mentions the fact that the ore, when thrown into pig iron on the Landore system, sinks through the 2 or 3 inches of slag; and that the sponge at Mr. Blair's works, instead of being porous, was compressed "until it resembled pure iron"-it is persumed in density. Of course it cannot be meant that, because lumps of ore fall through melted slag, sponge, even when compressed, will sink through liquid iron; nor is this very important, because the process of compression, being costly, is only applied to those portions of the sponge which, from their fine state of division, would be difficult to deal with in the open hearth furnace. As a fact, only about 40 per cent. of the sponge is so manipulated, the remainder being used as it comes from the retorts.

I possess no means of resuming my former discussion with Mr. Blair on this head by reference to direct experiment; and it is, perhaps, only due to Professor Tunner to observe that operations at Glenwood were suspended upon the occasion of his visit. It may be that I am mistaken in my views as to the actual way in which oxidation occurs; but that loss from this cause really does take place seems proved by the figures obtained from Mr. Blair himself. The knowledge of how this loss is occasioned is only important, so far as it might lead to the adoption of some means for its suppression.

Notwithstanding the reasons here given against the probability of a general adoption of the Direct process, it is still largely practised, as has been stated, in the United States. Its continuance, however, in my opinion, is not justified by any superiority in respect to economy, as compared with those processes which are dependent upon the blast furnace as a starting point. The Catalan works, generally speaking, are located where it would be inexpedient to incur the large outlay involved in the erection of modern ironworks. High prices, fostered by protective duties, may suffice, in ordinary cases, to afford fair returns to those who still pursue this primitive mode of working; and, in the event of the market value of the produce falling below prime cost, the extinguishing of a few Catalan fires or bloomaries is not a serious matter.

SECTION IV.

ON THE PRELIMINARY TREATMENT OF THE MATERIALS INTENDED FOR USE IN THE BLAST FURNACE.

IF the conclusions arrived at at the close of the last Section can be maintained, we must continue, for the present at all events, to look to the blast furnace as the starting point of those operations which have to furnish the world with iron and steel. This must at least be the order of things, until some considerable improvement takes place in that more direct process which has been suggested as an alternative

one.

This

It would conflict with the intense temperature required in the hearth of a blast furnace, if the materials, when they reached that point, retained any portion of those volatile constituents found with them in their natural state. Hence everything capable of being expelled by heat should be evaporated in the upper part of the structure. however implies a redundancy of heat in that region, and a sufficiency of time to accomplish this change in composition. In the larger furnaces, as recently introduced, this redundancy of heat does not exist; and in the older furnaces the necessary time, owing to their limited capacity, was not at the disposal of the smelter. Under such circumstances some preliminary treatment, as indicated by the heading of this Section, becomes necessary.

PRELIMINARY TREATMENT OF THE FUEL.

There is but one variety of fuel which in its natural state approaches the conditions required for smelting iron, viz. anthracite coal. This mineral in many cases, and particularly in the United States, contains a mere trace of volatile matter; and in consequence it reaches the hottest part of the furnace without any apparent change in its physical properties.

There are nevertheless many kinds of coal which, although very rich in volatile ingredients, are capable of being used in their raw state