The cost is still nearly the same at Merthyr, but it has been greatly decreased at Glasgow.
The saving of fuel by the hot-blast is said to be in fact so great, that blowing cylinders, which were adequate merely to work three furnaces at the first period, were competent to work four furnaces at the last period. The saving of materials has moreover been accompanied by an increase of one-fourth in the quantity of iron, in the same time; as a furnace which turned out only 60 tons a week with the cold blast, now turns out no less than 80 tons. That the iron so made is no worse, but probably better, when judiciously smelted, would appear from the following statement. A considerable order was not long since given to four iron-work companies in England, to supply pipes to one of the London water companies. Three of these supplied pipes made from the cold-blast iron; the fourth, it is said, supplied pipes made with the hot-blast iron. On subjecting these several sets of pipes to the requisite trials by hydraulic pressure, the last lot was found to stand the proof far better than any of the former three.—That iron was made with raw coal.
I have been since told by eminent iron-masters of Merthyr, that this statement stands in need of confirmation, or is probably altogether apocryphal, and that as they find the hot blast weakens the iron, they will not adopt it.
Between the cast irons made in different parts of Great Britain, there are characteristic differences. The Staffordshire metal runs remarkably fluid, and makes fine sharp castings. The Welsh is strong, less fluent, but produces bar iron of superior quality. The Derbyshire iron also forms excellent castings, and may be worked with care into very good bar iron. The Scotch iron is very valuable for casting into hollow wares, as it affords a beautiful smooth skin from the moulds, so remarkable in the castings of the Carron company, in Stirlingshire, and of the Phœnix foundry, at Glasgow. The Shropshire iron resembles the Staffordshire in its good qualities.
The average quantity of fine metal obtainable from the forge-pigs at Merthyr Tydvil, from the finery furnace, is one ton for 221⁄2 cwt. of cast iron, with a consumption of about 91⁄2 cwt. of coal per ton.
Estimate of the average cost of erecting three blast furnaces.
| BUILDING EXPENSES. | |
| Foundations | £480 |
| Masonry of hewn grit-stones | 600 |
| Common bricklayers’ work | 1200 |
| Lining of the furnace, hearth, &c., in fire-bricks | 1140 |
| Fire-clay for building | 80 |
| Lime and sand | 800 |
| CAST IRON. | |
| Cast-iron pieces, such as dam-plates, tymp-plates, beams, tuyère-plates, &c., weighing about 24 tons for each furnace;—in whole | 1140 |
| WROUGHT IRON. | |
| For the binding-hoops, keys, &c.; 5 tons for each | 300 |
| COST OF LABOUR. | |
| Bricklayers, masons, and labourers in building | 1080 |
| VARIOUS EXPENSES. | |
| Scaffolding | 48 |
| Tools | 160 |
| Shed in front of each furnace | 480 |
| Terracing, cost of ground, &c. | 2400 |
| Total cost of erecting the furnaces | 9908 |
| INCIDENTAL CHARGES. | |
| Blowing machinery, and steam engine of 80-horse power | 6400 |
| Inclined railway for mounting the charges | 120 |
| Gallery for charging | 160 |
| Steam engine house | 400 |
| Chimneys, boilers, &c. | 480 |
| Roasting kilns | 480 |
| Coke kilns | 800 |
| Dwelling-houses for workmen | 800 |
| Total cost of 3 furnaces complete | £19,548 |
Estimate from the Neath-Abbey Works in S. Wales, of the cost of machines requisite for a forge and shingling-mill, capable of turning out 120 tons of bar iron per week.