Old Hampshire Mapped

Copperas and Alum

Notes
dyeing In the late 16th and early 17th centuries there was a great interest to produce at home things which had hitherto been imports which were subject to the vagaries of international relationships, and religious differences between goverments: the alum trade was in the hands of the Pope. Two such items were Alum and Copperas, in greater demand by dyers because the home production of coloured cloths was increasing. Alum was a mordant for dyeing, as well as having uses by tanners, illuminators and painters. Copperas was a mordant, a black dye, and was used to manufacture black ink.

In 1562 William Kendall of Launceston, Cornwall, was granted a patent to manufacture alum in the southern counties of Britain. He began work on the Isle of Wight. This patent seems to have been ignored when another was granted to Cornelius de Vos, London, 1564, covering the whole of the kingdom. In 1566 James Blount, Lord Mountjoy, acquired this monopoly to work mines for alum and copperas in southern England, confirmed by an Act of Parliament which made it clear that Elizabeth I was anxious that the hidden riches of her realm should be found and put to good use, saving imports of this verie necessarie commoditie for the use of Draperye. Lord Mountjoy had recently inherited part of the manor of Canford, Dorset, including the heathland stretching along the coast east of Poole, and inland almost to Wimborne. Here, Canford, he had the right to dig ore and make alum and copperas, which he attempted vigourously, trying to clear other debts.

The mines eventually passed to the Earl of Huntingdon, who also poured capital and effort into development. Profits were made, though perhaps never as large as were hoped for. Lord Huntingdon, even when other properties were mortgaged against debts, kept the Canford property for its profits; he died 1595.

By the early 17th century the works at Canford were in decay, and other sources were being sought; in Guisborough, Yorkshire, but also in other parts of Dorset, at Smedmore and Kimmeridge for example, and on Brownsea Island in Poole Harbour. Various other copperas and alum production centres developed in the 17th and 18th centuries.

J H Bettey's paper, 1982, gives more much detail of the trade. Celia Fienes, quoted by H S Torrens, describes the process with a naive eye.

In various sources there are mentions of mines at Parkstone, Ockeman's House, and Canford Launds. Mynes next to Park Stone are clearly marked on Bowles map of Dorset, 1777. On Morden's map of the county are Mines just by Parke Stone. There were works at Boscomb, Alum Chine, and on Brownsea Island.

on maps The copperas industry is noted on early maps (do remember that some map makers copied from others without finding out whether the data was still relevant.)
Norden 1607 Bascamb Copperas house
Allomchine Copperas house
Both shown on his drawing of 1595, and the other versions of his map.
Speed 1611 Bascomb copperashouse
Allom house
Blaeu 1645 Bascomb Copperashouse
Allom house
Jansson 1646 Bascomb copperas house
Blome 1673 Bascomb copperas house
Morden 1695 Bascomb Coperas house
Morden 1701 Bascomb Coperas
chemistry The mineral being mined was iron pyrites, or just pyrites, iron sulphide, FeS2. This widely occuring mineral was formed in the sedimentary black shales of the Dorset coast under stagnant, anaerobic conditions.

Copperas is green vitriol or ferrous sulphate, FeSO4; in the old processes got from iron pyrites by weathering to get a liquor - sulphuric acid? which was used to dissolve any old iron. (Roughly!)

Celia Fienes, on Brownsea Island:-
... they gather the stones and place them on ground raised like beds in gardens, rows one above the other, and are all shelving so that the raine disolves the stones and it draines down into trenches and pipes made to receive and convey it to the house; that is fitted with iron panns foursquare and of a pretty depth at least twelve yards over, they place iron spikes in the panns full of branches and so as the liquor boyles to a candy it hangs on those branches: I saw some taken up it look't like vast binches of grapes, the cullour of the Copperace not being much differing, it lookes cleare like sugar-candy, so when the water is boyled to a candy they take it out and replenish the panns with more liquor; ... there are great furnaces under that keep all the panns boyling; it was a large room or building with severall of these large panns; they do add old iron and nailes to the Copperas Stones. ...

Alums are more complicated double sulphates of univalent and trivalent 'metals'; one example is potash alum, K2SO4.Al2(SO4)3.24H2O which is used as a mordant in dyeing.

Alum 'happens' in a natural state on some of the cliffs around Poole; thick incrustations which constantly peel off. The alum deposits in the Bagshot Beds exist as an impure double salt of aluminium and iron. Holly trees flourish where there is alum.

References (Mostly found in the Bibiography and Index of Dorset Geology by Jo Thomas and Paul Ensum, ISBN 0 900341 27 0)

Bettey, J H: 1982: production of Alum and Copperas in Southern England: Textile History: vol.13(1): pp.91-98

Cochrane, C: 1970: Poole Bay and Purbeck 300BC-AD1660::: but read sceptically

Fienes, Celia & Morris, C (ed): 1949: Journeys of Celia Fienes, The (1685-1703): Cresset Press

Garside, James E & Phillips, R F: 1953: Textbook of Pure and Applied Chemistry: Pitman (Bath, Somerset)

Hamilton, W R & Woolley, A R & Bishop, A C: 1975: Hamlyn Guide to Minerals, Rocks and Fossils: Hamlyn:: ISBN 0 600 34398 7

Hutchins, J H: 1861=1870 (3rd edn): History and Antiquities of the County of Dorset: vol.1: pp.647-51

Lehner, Sigmund: 1926: Ink Manufacture: Scott, Greenwood and Son (London)

Smith, H P (?): 1951: History of the Borough and County of the Town of Poole (?): vol.2

Sydenham, John: 1839: History of the Town and County of Poole

Torrens, H S: 1977: Copperice at Brownsea: Geological Curators group Newsletter: 1(9): p.449; reproduces Celia Fienes comments

Turton, Robert B: 1987 (reprint) & 1938: Alum Farm, The: Moon, Michael (Whitehaven, Cumbria)(reprint)

White, R: 1972: Alum and Copperas: Bournemouth Education Committee:: Environmental Studies Leaflet no.176