The Changing Technology of Post Medieval Salt Production in Hampshire
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Proc. Hampshire Field Club Archaeol. Soc. 67 (pt. II), 2012, 366–378 (Hampshire Studies 2012) THE CHANGING TECHNOLOGY OF POST MEDIEVAL SALT PRODUCTION IN HAMPSHIRE By JEREMY GREENWOOD ABSTRACT are almost unknown in southern England and salt in Hampshire has almost always been made The techniques of saltmaking in Hampshire evolved from sea water (Notholt 1973). to try to match the threats from salt production not Rock salt consists of virtually pure halite only in the UK but also from other sites around the (sodium chloride) – with organic inclusions – North Atlantic. This is an account of these changes whilst sea water contains various other evaporites; during the post medieval period compiled from first- notably the sulphates of magnesium and sodium hand accounts by those with hands-on experience of as well as magnesium chloride. Known as bittern saltmaking or scientists investigating the processes salts, these have a bitter, unpleasant taste as well involved. A (brief) first hand description of Hampshire as making salt deliquescent so that it ‘melts’ salt making was not published until 1682 (Collins when stored (Henry 1810). 1682, 15–31, 69) whilst a fuller report only appeared Salt was (and is) obtained from sea water in the mid eighteenth century (Brownrigg 1763, 32– by fractional crystallisation. As the sea water is 41) and was not updated until the beginning of the evaporated small amounts of calcium carbonate following century (Vancouver 1813, 420). and calcium sulphate are first deposited (Balarew 1993). Sodium chloride is the next to appear but it eventually overlaps partly with INTRODUCTION the deposition of magnesium sulphate (Epsom salt). The empirical art of the salt boiler was to Salt (sodium chloride) is essential for human extract the maximum amount of salt without existence. Whilst hunter-gatherer societies evident contamination by bittern salts (Aral have no need to supplement the salt occurring 2004). naturally in their diet, others require the use of additional salt for both dietary (domestic) and – increasingly – industrial reasons. PREHISTORIC SALTMAKING Modern commentators on the commercial manufacture of salt in Britain have generally There is a comparatively little evidence for pre regarded the industry in southern England Conquest saltmaking in Hampshire although as little more than a curiosity and sea salt comprehensive archaeological surveys have production generally has not received the been carried out. The results of archaeologi- attention it warrants compared with that cal investigations in Dorset and Hampshire paid to manufacture from rock salt (Adshead are currently being researched (S J Hathaway, 1992; Kurlansky 2003). English salt has been pers. comm.). At sites with a possible history of produced both from sea water and from rock production (intermittently) of upwards of 2000 salt (or natural brine springs emanating from years, archaeological evidence of early workings the latter) although low grade salt from the has often been destroyed by new saltworks con- French Atlantic coast was also refined to make struction over the centuries, erosion and the ‘salt on salt’, as at Southampton in the late rising sea level (Wessex Archaeology 2002; 16th century (HRO 44M69/G2/526). Com- Momber 2004). mercially significant rock salt (halite) deposits The earliest known method of coastal salt- 366 hants 2012b.indb 366 20/08/2012 10:12:59 GREENWOOD: THE CHANGING TECHNOLOGY OF POST MEDIEVAL SALT PRODUCTION IN HAMPSHIRE 367 making in Hampshire has been found from the occasionally seawater) to produce brine and late Bronze Age onwards and involved boiling filtered into sunken receptacles or ‘sumps’. seawater in crude clay dishes, supported by Leland describes the process in Lancashire: clay firebars. This technique was widespread throughout the world and these coarse ceramic ‘At the end of the sands I saw divers saltcotes, items (briquetage) comprise the main archae- where were divers heaps of sands taken of salt ological evidence for early salt making and strands, out of the which, by often wetting with trade (Poole 1987, 178; Tomalin 1989). This water they pike out the saltness, and so the water is derived into a pit, and after sodde’ technique continued through the Iron Age (Smith 1963, 98). and into the Roman period (at least), with vari- ations inevitably occurring (Hathaway 2005). The dumping of washed sand led to mound A wide range of types of briquetage items is formation which is often the only surviving known although interpretation continues to archaeological feature. No specific descrip- be a matter of dispute (Morris 1994). tions of the process exist as used in Hampshire No unequivocal evidence has been found for although it continued in use elsewhere well the use of evaporation ponds in this era (Pre- into the 19th century (Collins 1682, 14; historic Salt Production Methods, http://www. Brownrigg 1763, 47). Much of the evidence for seillevalley.com/Production.htm; S J Hathaway this technique has been destroyed by erosion, 2012 pers. comm.) agriculture or industrial development. The chronology of this change and its geographical spread is unknown although its dissemination MEDIEVAL SALTMAKING is likely to have taken centuries rather than decades (Wessex Archaeology 2002). Iron pans A major change in salt production technology were beginning to replace lead by the end of occurred from Roman times (in Cheshire at the 16th century although they had been in least) when brine began to be heated in wood- use in Durham since the 15th century (Surtees fired lead pans instead of primitive ceramic 1820, 94–104). containers, although evidence for such pans Thomas Wilkins obtained a description of a has not been found on the South coast until variation of this technique from old saltwork- the Anglo-Saxon period (Keen 1988; Holden ers in Lymington, before 1700, although it was & Hudson 1981). How and when the new obsolete by then; there is no indication as to technology was introduced remains unknown when this variation came to be practised: although the technique possibly spread from ‘The old saltworks were no bigger than one southwest France (Ridgeway 2000; Penney man could manage; they had only a small 2001). This development was accompanied by feeding pond and one large sun pan, which a major (possibly roughly concomitant) change they covered over with sand; and letting the in that seawater was no longer used as the water out of the feeding pond into it to wet the brine was first concentrated. Almost universally sand only; they let it dry in the sun after raking around the English coast, brine was made by it to make it dry the faster; and then they wet sand washing or ‘sleeching’ although this latter it again and this work they repeated until the term was not used in Hampshire and appears sand was very full of salt. to have been invented by archaeologists. This sand they shovelled up and carried it Between successive maximum spring tides, the to their clearer; and putting water to it, they sea water impregnated ground, near the high extracted a strong brine which they boiled up water mark, can dry out by natural evapora- in iron pans with a slow fire of wood or turf tion so that its surface contains dried salt. This or other fuel they could get; this made the salt surface sand, or alluvial deposit, (known as crast very large grained. or crust) was scraped off the beach (or other littoral site) and stored in barns until needed I have seen the remains some of these old (Ridgeway 2000; HRO 1570B/020). It was then saltworks which answer the aforesaid description placed in pits and usually washed with water (or but as the same grounds are now generally (espe- hants 2012b.indb 367 20/08/2012 10:12:59 368 HAMPSHIRE FIELD CLUB AND ARCHAEOLOGICAL SOCIETY cially at Lymington) turned into the new works; continued to be dependent on Continental salt there are no more to be seen of them that the suppliers until the French religious wars of the neat heaps of their sand used in the making their 1570s disrupted trade (Hughes 1934, 45). This brine and even these would not be known to have stimulated the setting up of many new coastal been sands but in the tradition of the people of saltworks in England, particularly on the East those places for the salt has so corroded the same and altered it; that it appears to be a rich mellow Coast, from the 1560s onwards, with Crown black soil and is very fertile for cabbages beans patents of monopoly (Hughes 1925, 334–51; and suchlike garden stuff and many farmers have BL Lansd. MS 59 no 66–70, 73 no 48–51; Lewis carried great quantities away to improve their 1953). This trend was later accentuated by the lands’ (Wilkins). prohibition on French and Spanish salt exports in 1630, after the disastrous English expedition This technique enabled a flexible approach to the Ile de Ré in 1627 (TNA SP 78/82). to be made to saltmaking by the producers who were predominantly small farmers as shown by the inventory evidence (e.g. HRO 1594 AD/50 POST MEDIEVAL CHANGES John Parsons of Downton, Hordle, husband- man). Before 1600, no person has been found Several of these patentees were from the Low who was exclusively engaged in commercial Countries and claimed to have knowledge of salt production. The salt ‘crust’ (or crast) could various ‘new’ and ‘superior’ methods of salt- be more easily stored and transported (short making but as these are never specified, there distances) than brine and the salt could be is rarely any description of them. In 1564, extracted at any time; as required. No large Francis Berti of Antwerp began shipping iron capital investment was required; inventories pans and other implements for making salt to in Hampshire typically value saltern leads at England, from Bergen op Zoom, consequent about 15–20 shillings and utensils at around to his exclusive grant of making white salt in 15 shillings; for example that of Thomas Fox England for 20 years (TNA SP 12/36 f.