Kaolin is dissolved feldspar, deposited from the granite which has yielded to atmospheric and aqueous influences.
The white clay is dug out of pits and then is washed in tanks, in which the clayey sediment is collected. This sediment has, however, first to be purged of much of its mica and coarser particles as the stream in which it is dissolved is conveyed slowly over shallow "launders."
At the bottom of the pits are plugs, and so soon as the settled kaolin is sufficiently thick, these plugs are withdrawn, and the clay, now of the consistency of treacle, is allowed to flow into tanks at a lower level. Here it remains for three weeks or a month to thicken, when it is transferred to the "dry," a long shed with a well-ventilated roof, and with a furnace at one end and flues connected with it that traverse the whole "dry" and discharge into a chimney at the further end of the building. On the floor of this shed the clay rapidly dries, and it is then removed in spadefuls and packed in barrels or bags, or merely tossed into trucks for lading vessels. The clay is now white as snow, and is employed either in the Staffordshire potteries for the manufacture of porcelain, or else for bleaching—that is to say, for thickening calicoes, and for putting a surface on paper. Some is employed in the manufacture of alum; a good deal goes to Paris to be served up as the white sugar of confectionery, and it is hinted that not a little is employed in the adulteration of flour. America, as well, imports it for the manufacture of artificial teeth.
Great heaps of white refuse will be seen about the china-clay works; these are composed of the granitic sandy residuum. Of this there are several qualities, and it is sold to plasterers and masons, and the coarsest is gladly purchased for gravelling garden walks. The water that flows from the clay works is white as milk, and has a peculiar sweet taste. Cows are said to drink it with avidity. The full pans in drying present a metallic blue or green glaze on the surface.
The kaolin sent to Staffordshire travels by boat from Plymouth to Runcorn, where it is transhipped on to barges on the Bridgewater Canal, and is so conveyed to the belt of pottery towns, Burslem, Hanley, Stoke, and Longton.
The Dewerstone towers up at the junction of the Meavy and the Plym. On the side of the Plym there are sheer precipices of granite standing up as church spires above the brawling river. The face towards the Meavy is less abrupt, and it is on this side that an ascent can be made, but it is a scramble.
On reaching the top, it will be seen that the headland has been fortified by a double rampart of stone thrown across the neck of land. Wigford Down is in the rear, with kistvaens and tumuli and hut circles on it.
The visitor should descend in the direction of Goodameavy, and thence follow down the river that abounds in beautiful scenes. It was formerly believed that a wild hunter appeared on the summit of Dewerstone, attended by his black dogs, blowing a horn. From Dewerstone the visitor may walk to Bickleigh Station, and take the train for Tavistock, which I have written about in my Book of the West, and will not re-describe in the present work.
FOOTNOTES:
[21] I have given it, with the original air, in the Garland of Country Song. Methuen.