By Alan Telford, Project Supervisor

While he’s working from home, Al has been reading up about some of his favourite post-medieval archaeology! This blog is summarised from a longer piece that you can download here…

Although parts of the county are currently some of the most heavily industrialised in the UK, Lincolnshire is often regarded as an agricultural county. In the past this was even more marked: the 1851 census records 52,046 agricultural labourers and 11,048 farmers. As someone who grew up on Tyneside, and with a keen interest in industrial archaeology you might think that there would be little of interest to me in Lincolnshire… HOWEVER, the industrial revolution did happen here! It took place about 35 years after it was over in some other places, and of course was strongly linked to agriculture. So what better place to start exploring it than with fertiliser and specifically with…

Superphosphate!

Essentially the first of the chemical manures, the use of bone dust as a fertilizer in the UK is thought to date to the 18th century and has been attributed to the sale of bone dust as a by-product from the cutlery workshops of Sheffield. The presence of phosphorus in bones was recognised in 1769 by the Swedish chemist and metallurgist Johan Gottlieb Gahn, but the use of untreated bone dust as a fertiliser has limited use, as the phosphates are insoluble in water, and can’t be taken up to any great extent by the crop. In 1842 John Bennet Lawes was granted a patent and began the production of superphosphate at Deptford Creek in London. Manufacture soon spread to Lincolnshire. The method used was very simple, essentially involving throwing a load of vitriol (sulphuric acid) onto a heap of crushed and/or burnt bones, in a large room known as a den. Inevitably the process became more complex over time, with bones replaced by an array of ‘phosphate rock’, a catch-all term for materials that included Peruvian guano and coprolites (fossilised poo), first extracted in the UK in Suffolk in 1847. The sulphuric acid required in the manufacturing process was difficult to transport, so establishing vitriol plant on site was a logical step. This was certainly true of the chemical manure works of John Jekyll, established in 1856 on Carholme Road in Lincoln, which certainly was producing vitriol and superphosphate by 1897. Jekyll’s works eventually became part of Fisons, and the site currently lies beneath the ‘Roman Wharf’ development. Another chemical manure works worthy of note is that at Hubbert’s Bridge, to the west of Boston, still largely survives.

Slag!

Although superphosphate was the most common phosphatic fertiliser used during the 19th century, in the 20th century another important source of phosphates was manufactured in Lincolnshire from basic slag, a by-product of the steel industry. In 1888, Maximilian Mannaberg, established a basic open-hearth plant comprising two 15-ton furnaces and the integrated iron and steel works of John Lysaght and Co. at Normanby Park, was producing steel from 1912. Following the First World War steel plants were erected at Appleby-Frodingham, Redbourn Hill and the Trent Ironworks . Basic slag was a by-product of basic (as opposed to acid) steelmaking, which was developed from 1879 as a way of using iron ores with high phosphorus content. The phosphorus passed into the slag and could be ground into a fine powder and used as fertiliser. By 1910, the UK was producing somewhere between 600,000 and 850,000 tons of basic slag and 733,262 tons of superphosphate.

Sulphate of Ammonia!

I expect everyone is wondering about the production of nitrogenous fertilisers in Lincolnshire! Equally if not more important as phosphates, the main source of nitrogen fertiliser in the 19th century was sulphate of ammonia, produced by the distillation of ammoniacal liquor produced as a by-product of gasworks and coke works. By 1882 Lincolnshire had around a dozen gas undertakings, and in the early 20th century the coke ovens at both Redbourn Hill and Normanby Park iron and steel works were producing sulphate of ammonia. The national figure for the production of ammonium sulphate in 1910 is 367,587 tons, of which 167,820 tons were from gasworks and 92, 665 tons from coke works and constituted an important part of the chemical industry in Lincolnshire.

Our Northeast office has moved to new, larger premises in Chester-le-Street, with room for future expansion, meetings and a cafe too! After a few days of unpacking and building furniture, our Regional Manager for the Northeast and Scotland and Business Development Manager, Craig Huddart is all set. The opening of the new office is just the latest phase of our expansion and Craig is really excited and proud to be the person spearheading it. The Northeast and Scotland are thriving places, with stunning scenery and coastlines, renowned for outstanding heritage assets and amazing archaeology. We’re building on an existing foundation of clients and projects and Craig is looking forward to welcoming new clients and schemes to our portfolio. So if you are looking for archaeological advice or work to support a planning application, thinking of starting a community project or perhaps in need to a geophysical survey, give Craig a call. Contact details can be found here.