The early diaries contain fascinating accounts of Henry’s experiments to produce higher yields of suitable good quality iron at lower cost (iron was graded according to its quality with particular grades used for specific products). Success meant higher company profits, approbation from his brother, Richard, and a hard earned salary bonus. Henry spent long hours at the works and rolling mills trying to minimise any impurities in the finished iron which could compromise its strength and/or malleability.
The iron making process began with smelting the raw materials – iron ore, coke and limestone – in the blast furnace. Early Welsh ironworks depended on locally mined iron ore, often of a type known as ‘blackband’ (essentially ironstone containing coal), but by the 1860s it became more cost effective to import haematite ore from Cumbria or Spain. Haematite ore, which had a higher metallic content than blackband, was often heated in the absence of air to remove moisture and non-metallic impurities before smelting, a process known as ‘calcination’. Calcination converted the ferrous oxide within the haematite to ferric oxide, Fe2O3.
Calcined haematite, coke and limestone would be loaded (‘charged’) into the top of the furnace and heated. A steam powered engine would blast hot air through openings (‘tuyeres’) near the furnace base to maintain the temperature and oxygen supply. Carbon monoxide (from the coke) would reduce the ferric oxide (from the haematite) to form molten iron while impurities would combine with calcium carbonate (limestone) to produce slag which floated above the iron. The liquid iron could then be tapped and run off into moulds known as pigs.
Pig iron was converted into wrought iron by ‘puddling’. Patented by Henry Cort in 1783, puddling involves reheating the pig iron in a reverberatory furnace (a furnace in which the fuel does not come into contact with the product). The ‘puddler’ stirred the molten iron through an aperture in the puddling furnace with a long hooked rod. As the residual carbon was burnt off, the melting point of the iron increased causing semi-solid lumps of iron to appear. At the critical moment, the puddler used his rod to work the lumps together to form a single mass or ball which he quickly removed, either to a second puddling furnace for further refining or to the forge for hammering or rolling, depending on the quality of iron needed. Hammering and rolling squeezed out any dross. To further improve quality and to ensure the finished product had a uniform consistency, iron bars were cut up, piled (by ‘pilers’ who were often women or girls), tied together with iron straps, reheated and then rolled once more.
The properties of the finished wrought iron also depended to a large extent upon the level of residual impurities contained within it. Carbon, silicon, phosphorus and sulphur all affected the metal’s durability, strength and malleability. Too much carbon made the metal too brittle, too little made it too soft. Getting the correct balance was often a case of trial and error. Henry, though, was determined to take a more scientific approach, even attending chemistry lectures. He describes many of his experiments in his diary [D553/3]:
p.147-48, Tue 27 Jan 1863,…up to Works met Richard; trying lots of experiments with bits of Rail under Hammer, and in nitric acid; had report of assay from Dr Noad of the Forge cinder, the piece simply calcined contains sulphur 1.43 per cent, the cinder calcined and afterwards re-calcined for 24 hours in a puddling furnace and afterwards allowed to cool gradually on the ground contained sulphur 0.306 per cent, the cinder that went through the same process as the latter, but was cooled immediately in water contained sulphur 1.26 per cent, so the water apparently did away with nearly all the good of the second calcining, and seemingly during the action of cooling while exposed to the atmosphere is the time when the sulphur is disgorging itself from the cinder, and not while so long in the fire; re-calcined some more today only keeping it in the Puddling Furnace about an hour to heat it red hot through and after cooling gradually, sent a piece of it and a piece of the same lot not re-calcined to Dr Noad again to see the result of only heating through.
p.154, Wed 4 Feb 1863, ..Letter and result of assay of cinder from Dr Noad that I sent him 27th inst: sulphur in cinder simply calcined but solid 2.28 per cent; sulphur in cinder calcined and heated again through for an hour in Puddling furnace 1.75 per cent…
Dr Henry Minchin Noad, Fellow of the Royal Society, was a Professor of Chemistry at St George’s Hospital, London.
One way of increasing the iron yield was to add copperas to the furnace. Despite its name, copperas has nothing to do with copper. It is the common name of crude ferrous sulphate, FeSO4.7H2O, which converts on heating eventually to ferric oxide, Fe2O3 (the same oxide found in haematite).
D553/6, p.10, Wednesday 28th October 1863, Sent to Jones for copperas to mix with the pig iron in Forges while it is boiling. Richards idea to try if it improves the quality of the iron, it comes from tin works.
p.21, Saturday 7th November 1863, Wrote The Ystalyfera Iron Co. for two casks of Copperas to try again in puddling Furnaces.
Another way was to use a cast iron base in the furnace instead of sand:
D553/1, p.72, Sun 29 Oct 1860, Mill here working busily on 10 furnaces trying an experiment with a cast iron bottom instead of sand.
Henry also experimented with the way wrought iron bars were piled:
D553/4, pg.1-2, Thu 19 Feb 1863: Back to Hirwaun 1st train; I to mill at 8 o clock and saw 2 Rails rolled, Bombay D. H. section, from piles made as follows, 8 x 2 in slab (of all metal piled in our usual way and worked edgeways) top and bottom, 2 – 4½ x 1/8 pieces of metal next each slab and remainder of pile (to form centre of Rail or Stem) Boiling 8 in: wide in two pieces as usual; (mistake above) slabs 8 x 2 in: not made in ordinary way but made thus, all metal Bars piles 9 in: wide and on their flats up 6 in: solid in the pile; the remaining 3 in: wanted to complete proper height of pile composed of metal bars 1 1/8 in thick 3 in: wide, 9 in: long and piled edgeways across the piles, to within 3 in: of each end of pile, which 3 in: was filled up with 3 small pieces of metal lying flat, so as to keep up in their position the series of pieces of metal standing on edge, this pile rolled flat made a scandalous bad Bar, cracking across the surface from end to end; the two Rails however though made with such bad looking slabs came out perfectly good in the heads; 2 other Rails I had rolled with 8 x 2 in: slab of ordinary make for one head, and the other head, made from a series of 8 x 3½ x ¾ No 2 Blaina Iron Bars placed across pile edgeways the same way as the metal in pile for slab as explained above, the blooming of this pile tore the pieces apart much….
Much of the iron was used to make rails and chairs for the rapidly expanding rail network, at home and abroad, particularly in India. Many ironworks employed their own inspectors responsible for quality control. However, railway companies often preferred to send their own to monitor production – a source of irritation for Henry and his brother, George, at Taff Vale.
John Addis relates the following story allegedly told by Mr Bateman, the Fothergill’s London agent, to James Dolphin, an employee of the Crawshays:
When the Inspectors make any fuss as to the Rails being of bad quality and not according to specification, Mr. Bateman takes it upon himself to order 2 or 3 Rails made entirely of No.2 Iron and frequently some of the whole of which are No. 3. These are sent up to the Engineers and Headmen of the line or Company whom the rails are for, who are of course delighted with them. This quite upsets the Inspectors and they never take any more trouble about looking after them and let them all pass [Addis, John P. (1957) The Crawshay Dynasty: A study in industrial organisation and development, 1765-1867. Cardiff: University of Wales Press, p.121].
It’s unlikely the Fothergill brothers were ignorant of Bateman’s fraudulent practice of filling an order with No. 1 Rails (the lowest grade iron) when the Rail Company had inspected No.3. Is this something Henry himself condoned or did he just turn a blind eye?
Still, Aberdare rails were held in high enough regard to attract the interest of the millionaire railway entrepreneur, Sir Samuel Morton Peto, who met Henry while visiting the works in January 1863. Sir Morton, who was instrumental in building many London landmarks, including the Houses of Parliament and Trafalgar Square, was awarded his baronetcy for building railways in the Crimean War to supply British troops.
Competition between the South Wales iron works was fierce. Reading the details of Henry’s experiments, I wonder whether Henry was also competing with himself.
Corinne Evans, Glamorgan Archives Volunteer