The same mixture of gases was then tried on calcined Clevelar ore also broken to the size of mustard seed and containing 437 p cent. of iron. Six litres were passed in two hours over 10 grammes ore, the temperature being maintained at 1,000° C. 1,832° F during which time the metal lost 88 per cent. of its original oxyge The weight of the six litres of water-gas, namely, 4:018 grammes, w increased to 5.712 grammes after passing over the ore.

The gas after passing over the ore would have the following average composition in 100 parts by weight:

1.-Oxidized gases.-Carbonic acid... 395 Water vapour 17-2 = 56-7 2.-Unaltered gases.-Carbonic oxide 40.5 Hydrogen

2.8

43.3

By weight 1 of C as CO, is accompanied by 1'61 of C as CO.

2

Showing 1.535 of reducing gases to 1 of C and H as oxidizing

gases.

By measure 100 volumes of the reducing (CO and H), are associated with 6.5 of the oxidizing, gases. Over ten grammes of the same ore as that used in the former experiment 6 litres of pure water-gas was passed, equal to 60 litres per 100 of ore; the temperature as before being 1,000° C. 1,832° F.

Calculated on 100 grammes we have the following numbers:—

Reduced ore, equal to 83.53 grammes, as placed beyond the 100 grammes of calcined ore so that the water-gas, partly converted into water and carbonic acid, passed over it.

.33

Difference due to experimental error and carbon deposition

The escaping gases were also examined with the following results:The 60 litres, calculated on 100 grammes of calcined ore, consisted of 30 litres of carbonic oxide, or 37.50 grammes, and 30 litres, or 2.68 grammes, of hydrogen =40 18 grammes of original gas raised to 57.12 grammes in the former experiment. By the loss of oxygen absorbed by the metallic iron the weight was now reduced to 52:39 grammes, and 100 parts by weight consisted of

1.-Oxidized gases.-Carbonic acid 32.6 + Vapour of water 12.8 45'4 2.-Unaltered gases.-Carbonic oxide 508 + Hydrogen

3.8

54.6

By weight.-1 of C as CO, accompanied by 1·24 of C as CO.

Showing 1-75 of reducing gases to 1 of C and H as oxidising gases. By volume 100 volumes of reducing gases (CO and H) are associated with 39 of oxidising gases.

In the experiment just described the oxygen removed from the calcined ore (by H 5.99 grammes and by CO 6.22 grammes) was 12.21

3

f

grammes; while the reduced ore took up only 3:16 grammes or a little under 26 per cent. of that lost by the oxidized ore, both containing the same quantity of metallic iron.

There is not the slightest reason to suppose that the immense surface of highly heated iron which fills the interior of a blast furnace would not amply suffice, so long as it retained the temperature proper to the smelting process, to decompose all the carbonic acid and vapour of water exposed to its influence. Admitting however that only 26 per cent. of the metal was re-oxidized, and taken up, as it would be, by the slag, the cost of the remainder of the iron would be raised to a corresponding extent-not to speak of the physical difficulty of working a blast furnace in which one-fourth of its iron was running over the slag notch. Instead of cast iron we should, under the supposed conditions, have an infusible mass and a cinder, the corrosive action of which no brickwork could withstand.

What the ultimate fate of the furnace itself would be under such a mode of treatment we shall probably never know, for it is not to be supposed that the operation would be continued long enough to supply us with this information.

I met recently with the account of an experiment in which an attempt was made to drive a furnace partly with coke and partly with watergas. On the circumstances and conditions of this experiment I should like to say a few words; because they seem to me to confirm the general views just laid down. A small furnace was constructed, 21 feet high, in which with blast heated in a Cowper's fire-brick stove a few cwts. only of metal were made per day with an expenditure of about 7 tons of coke per ton of iron. No information is given to account for the singularly defective character of these results. Forty years ago I worked a furnace 20 feet high-of larger diameter it is true; but out of it 7 tons a day were run with an expenditure of only 2 tons of coke per ton of metal, although the blast was under 650° F. To the furnace now referred to water-gas was then applied-not alone as has been intimated, but with the retention of a considerable quantity of coke, which was introduced into it with the ore and flux. The daily produce, in 24 hours, was then about 6 tons and the consumption of coke per ton of iron was:—

The temperature of the blast is not given; but that of the watergas is stated to have been 600° C. (1,112° F.) exactly that previously assumed in these pages. The limestone per ton of iron was under 4

cwts.

The description of the experiment does not contain the details necessary for making any critical examination of all the results; but it is stated, that operations had to be suspended owing to the " "chilling" of the furnace. This difficulty was ascribed to the quantity of moisture in the ore the oolitic of Luxemburg-which contained in all 19.50 per cent. of volatile matter. To expel this, probably a couple of cwts. of coke would have sufficed on each ton of iron made.

I am however confirmed by what is said, in my view of the oxidizing tendency which the presence of carbonic acid and vapour of water must confer on the gases of the hearth; for it is stated in the account given of the trial that the mineral used contained 34.50 per cent. of iron, while the pig iron produced only corresponded to a yield of 25'6 per cent. Here then we have a furnace within which and independently of the water-gas nearly as much coke is consumed per ton of metal, as would alone in the ordinary blast furnace suffice for its production, and at the same time actually wasting 25 per cent. of all the iron in the ore-no doubt by the oxidizing character of the products of the combustion of the water-gas, that combustion being obtained at the expenditure of 25.74 cwts. of coke on the ton of iron.

While admitting that the dimensions of this experimental furnace were not such as to command any large measure of success, to my mind the indications it has furnished, confirm the opinion that for reducing iron in a blast furnace water-gas will be found entirely unsuited. That the introduction of a moderate quantity of this form of fuel, in the way practised and abandoned by Mr. Dawes many years ago, may, while wasting a portion of the iron, partly free the remainder from silicon and phosphorus, is not impossible.

When in the discharge of my duty as a judge at the Philadelphia Exhibition in 1876, my attention was drawn to a specimen of iron described as having been smelted with petroleum injected at the tuyeres. No information was given as to the circumstances under which it was produced.

The experiment has been repeated by Mr. E. W. Shippon1 of Meadville in Pennsylvania, who forced in a stream of this oil previously heated. At the commencement of the trial the furnace was being worked with vegetable fuel; and although the temperature of the hearth previously was satisfactory, the moment this liquid hydrocarbon was introduced, the cooling effect was such that it was no longer possible to effect a separation of the iron from the slag.

Journal of United States Association of Charcoal Workers, Nov., 1882.