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Jan. 8, 1839.
The PRESIDENT in the Chair.
Ar the close of the last session, a discussion took place on the use Use of of peat in the manufacture of iron, and it was stated that the late Peat Fuel. Mr. Wilkinson, of Gateshead, smelted iron with peat fuel, and that the tools made from that iron were of a superior quality: that this iron was more malleable than Swedish iron.
Mr. Mushet was not aware that the smelting of iron with peat fuel had been recently performed. He could not conceive that the mere working of iron from bar into horse-shoes could produce any sensible effect; were the whole process conducted by peat fuel, the quality might be affected. He did not believe that peat could be used in the puddling furnace; it might, however, in the refining. It might be used in the smelting furnace, but with a diminished produce. For welding a hollow fire is necessary, and peat will not readily make a hollow fire; iron may be improved in point of hardness by the use of peat. He had analysed many kinds of peat, and never found one to contain less than 5 per cent. of earthy matter; many contain 20 per cent.; coal seldom contains more than 4 per cent. The common bog peat contains 25 per cent. of carbonate of iron.
Several present bore testimony to the improvement in the working of iron by the use of peat, and that better weldings were made by it in consequence of its freedom from sulphur. The absence of sulphur in peat was denied by Mr. Lowe, who had used it for making
gas at Amiens, and the quantity of sulphuretted hydrogen produced in the purifiers was very great. The Newcastle coal varied much in its qualities; some is exceedingly bituminous, making abundance of gas, but abounding also in sulphur and pyrites. He never met with any coal which did not produce sulphuretted hydrogen-thus proving sulphur to be an element of coal. The Tanfield coal is peculiarly free from sulphur. Dr. Smith remarked on the great influence which the strata had on the quality and nature of the peat; that the Dartmoor peat differs from all other peat in that it burns with a red ash.
It was remarked that the smiths in Cornwall owe much to their long practice in the use of peat, just as the smiths of Pembrokeshire have learned to use anthracite. Both, however, would probably use pit coal, could it be easily procured.
The conversion of iron into steel was discussed, and it was stated that iron could be converted into steel by immersion in pure carbon, as in the Macintosh process, at the rate of 1-30th of an inch per hour. Mr. Roberts stated the success of case hardening depended on the gentleness of the heat. Great care must be taken not to overheat, and case hardening might take place to the depth of 3-8ths of an inch in four or five hours. It was stated to be cyanogen united with iron which produces case hardening, but carbon which produces steel. An instance was mentioned by Mr. Carpmael in which animal charcoal was used for case hardening the interior, and vegetable charcoal for softening the exterior. Allusion was made to the fact, that the most perfect chill is obtained by the employment of moulds red hot.
Mr. Farey alluded to the charcoal, or peat coke, which Mr. OldCharcoal. ham employs at the Bank of England; this is in thin cakes, and denser than the heaviest wood. Mr. Bramah remarked on the great value of compressed peat, could it be procured at a marketable price, on account of its superiority as a fuel for making large weldings.
The preceding minutes having been read, Mr. Parkes stated that the greater part of the charcoal used in Paris is from peat. The peat charcoal is preferred to the very best wood charcoal. There
are two modes of making this charcoal; In a Swedish furnace, which is an oven made of lumps of peat the pieces to be carbonised are placed in the interior, ignited, and smothered up in the usual manner. The other mode consists in getting peat as dense as coal, by allowing the small atoms to come within the natural force of cohesion. The peat for this purpose is dredged up from the bottom of streams, and laid up to dry, and formed into small bricks, which, on drying, contract very much. Compression will not do. In Holland they dig the turf and put it into running water. The water cannot be driven out by pressure. He had seen peat compressed with a force equal to that for pressing bowls for calenderers, but it was not near so dense as that formed by the natural means just alluded to. Mr. Pellatt remarked, that the coking coal does not deprive it of the sulphur. Washing the coke will remove much that remains; but even then it cannot be used for welding glass—nothing but the purest beech wood will serve for this. Charcoal will not answer, as it requires a flame. By welding, he meant the operation of putting a handle on a vessel. The glass being of a proper temperature, a union is formed, provided no sulphur be present.
Mr. Lowe remarked, it had been practically found that beech charcoal is valuable because of the quantity of carbon it contains. There is more pure carbon in a given weight of beech wood than of any other kind. Oak is the next best.
Jan. 29, 1839.
BRYAN DONKIN, V. P., in the Chair.
"On framing Lock Gates without Iron Work." By S. Ballard, A. Inst. C. E.
The ledges, or horizontal pieces, are held to the back and mitre Lock post by dovetail tenons and wedges; thus avoiding the use of iron T pieces and screw pins, which occasion the wood in immediate contact with them to decay, while the parts not pierced with iron are perfectly sound. This method was adopted in some gates on the Herefordshire and Gloucestershire canal, and after some years' experience, is found completely successful. Tar and white lead are put into the mortices, and the wedge driven down upon it, so that every crevice is filled, and the joints rendered water-tight; the planks, also, are fastened on with oak pins instead of nails.
Some discussion took place on the general opinion, that when dis