Historical maps and records of salt areas often reveal the locations of brine springs through their place names. In Roman times, sources of salt were noted as Salinae and in Medieval times the locations of salt springs were indicated by the suffix wich or wyche. Many of these places were further differentiated so that, for example, in Cheshire, the towns of Nantwich, Middlewich and Northwich were established. Nantwich refers to the named wich (Nametwilhc in 1194), Middlewich to the middle wich and Northwich to the northern most wich. Likewise in Droitwich the different springs were individually named as Netherwich, Middlewich and Upwich corresponding to their places in the town and lower, middle and upper locations along the River Salwarpe (possibly derived from the Roman name of Salinae). Many other places include wich or wyche as prefix or suffix, such as the administrative district for Droitwich is Wychaven.
Although little evidence remains it is documented that the natural brine springs at Northwich were used in pre-Roman times. At Droitwich a possible Iron Age brine boiling hearth was excavated at the site of the Upwich brine spring and probable remains of Iron Age salt pits were found nearby. The Roman remains at Upwich were extensive and showed a well-organised salt industry with a wood-lined well and a probable brine lifting structure. The importance of Droitwich as a salt producer in Roman times is indicated by its Roman name of Salinae, a name also applied to Middlewich and used for Saltzburg in Austria. Droitwich has been recognised as the Salinae noted in Claudius Ptolemy's Geography compiled in ca. 140-150 A.D., and as the place named Salinis noted in the Ravenna Cosmography compiled soon after 700 A.D. The Roman names and archaeological evidence indicate that brine was flowing to the surface at Droitwich, Middlewich and Northwich since before the start of written history. The Early Medieval period or Dark Ages is poorly documented, but one of the earliest references to Droitwich salt was in 716 when King Ethelbald granted a salt pit on the south side of the River Salwarp to Evesham Abbey. Salouuarpe (Salwarpe) was also mentioned in 817 and brine springs and salt furnaces were recorded at Droitwich in 816 and 906. In 962 A.D. Bishop Oswald granted Beonetlaege (Bentley) four salt pans at Upwich (Droitwich) and enough woodland at Bradanlaege (Bradley) to fuel them. Wychbold was mentioned in 692 and Saltwic (Droitwich) in 884-901.
The brine extraction and boiling industry established by the Romans flourished in Medieval times and was well documented in the Domesday Book. This was compiled for William 1st as an inventory of his newly acquired lands in 1084-1086, with numerous "wiches" and salt houses recorded. Many places are noted in the Domesday Book as having "salt houses" but commonly they belonged to estates outside of the salt areas, and many of the entries note ''salt houses at wich'' without stating exactly the wich to which they refer. At Droitwich King William had 85 salt pans and 68 manors and estates which had the rights to receive salt. Several dedicated roads or "salt ways" were established to transport the produce with some of these dating back to Roman times. Places recorded in the Domesday Book and younger documents, which certainly had salt springs and salt pans, include Droitwich (Wich 1086, Drilhtwych 1347), Middlewich (Wich, Mildestuich 1086), Nantwich (Wich 1086, Nametwilhc 1194), Northwihc (Wich, Norwich 1086), Salt (Selte 1086), Wychbold (Wicebold 1086), Salwarpe (Salewarpe 1086. The importance of Droitwich as a salt producer is shown by the fact that in 1215 King John gave Droitwich its charter in exchange for a yearly rental of £100 for the salt springs.
The extraction of minerals including salt in Medieval times was documented by Georgius Agricola (1494-1555) in his book De Re Metallica published a year after his death. His profusely illustrated book described and illustrated practices in all sorts of mining. This work would not be so well known if it was not for the efforts of US President Herbert Hoover, a former mining engineer and his wife Lou a Latin scholar. Between them they translated the work and published it in 1912; it is available online as a flip-book . Although Agricola’s illustrations illustrate mining in Bohemia, the practices were similar elsewhere and the methods of salt extraction and processing described by him have been used to interpret archaeological excavations at Droitwich and in Cheshire. The two illustrations from Hoover and Hoover’s translation presented here show brine wells and the processing of the salt.
Most of the early records of salt springs relate to deeds, land ownership changes and taxes, but in the 17th Century the scientific investigation of numerous natural, physical and chemical phenomena began. In 1669 William Jackson, a ''Doctor of Physik'', reported details of the Cheshire salt springs to the Royal Society. Jackson's description of the Cheshire salt springs notes that the salt pits were 3-4 yards deep (2.7-3.6 m), although at Nantwich the spring was 7 yards (6.4 m) from the surface. He noted that the salt was aggressive to vegetation and that the water in the brine pits was very cold. In addition, he recorded that there were numerous mosses with turf which could be cut, dried in the sun, and presumably used for fuel. He recorded that:
"a place of My Lord Cholmondeley's, called Bilkely, (now Bickley) about 9 or 10 years since, not far from one of these mosses, without any earth-quake, fell in a piece of ground about 30 yards over (more than 27.4 m across), with a huge noise, and great oakes growing on it fell with it together; which hung first with part of their heads out, afterwards suddenly sunk down into the grounds so as to become invisible"
Another record of this subsidence is presented by Ormerod (1848) who noted that the event took place on 8 July 1659 at the place called Barrel-fall, and that it was now dry and overgrown with brushwood. As part of his scientific work, Jackson (1669) recorded and measured the concentration of salt in the brine, noting that the strongest spring at Midlewich (Middlewich) yielded one fourth part of salt, but had a low flow. By contrast, the one at Nantwich yielded one sixth part and had a large yield. He found that the strength of the brine was stronger when the pit had been left to rest and not exploited for some time. The production of crystallised salt for each day was given as 450 bushels from Upwich, 40 bushels from the best pit at Netherwich and 30 bushels from the worst pit. A bushel has a volume of 8 imperial gallons (36.4 l) which (using a dry density of 1.154 for loose salt crystals from the Salt Institute website) would equate to about 42 kg of salt in a bushel and a daily salt extraction at Droitwich of about 21,840 kg. Using a specific gravity of 2.165 for solid crystalline salt, this would correspond to about 10 m3 of rock salt a day dissolving naturally in the surrounding area to feed the springs.