Of the state of the Staffordshire potteries at this period, the latter half of the seventeenth century, Dr. Plot gives a most interesting and valuable account, in which he shows not only what clays were then used, but also speaks of the glazes, and describes the modes of manufacture of some of the vessels. The clays, it appears, were mostly procured from the coal measures, and fine sand to temper and mix with them was procured from Baddeley Edge, Mole Cop, and other places. The following is Dr. Plot’s account:-- “25. Other potter’s clays for the more common wares there are at many other places, particularly at Horsley Heath, in the parish of Tipton; in Monway field above mentioned, where there are two sorts gotten, one of a yellowish colour, mixt with white, the other blewish; the former stiff and heavy, the other more friable and light, which, mixt together, work better than apart. Of these they make divers sorts of vessels at Wednesbury, which they paint with slip, made of a reddish sort of earth gotten at Tipton. But the greatest pottery they have in this county is carried on at Burslem, near Newcastle-under-Lyme, where for making their different sorts of pots they have as many different sorts of clay, which they dig round about the towne, all within half a mile’s distance, the best being found nearest the coale, and are distinguish’t by their colours and uses as followeth:-- “1. _Bottle clay_, of a bright whitish streaked yellow colour. “2. _Hard fire-clay_, of a duller whitish colour, and fully intersperst with a dark yellow, which they use for their _black wares_, being mixt with the “3. _Red blending clay_, which is of a dirty red colour. “4. _White clay_, so called it seems, though of a blewish colour, and used for making yellow-colour’d ware, because yellow is the lightest colour they make any ware of. All which they call _throwing_ clays, because they are of a closer texture, and will work on the wheel. “26. Which none of the three other clays they call _Slips_ will any of them doe, being of looser and more friable natures; these, mixt with water, they make into a consistence thinner than a Syrup, so that being put into a bucket it will run out through a Quill. This they call _Slip_, and is the substance wherewith they _paint_ their wares, whereof the “1. Sort is called the _Orange Slip_, which, before it is work’t, is of a greyish colour, mixt with orange balls, and gives the ware (when annealed) an orange colour. “2. The _White Slip_: this, before it is work’t, is of a dark blewish colour, yet makes the ware yellow, which, being the _lightest_ colour they make any of, they call it, as they did the clay above, the _white slip_. “3. The _Red Slip_, made of a dirty reddish clay, which gives ware a black colour.