Fuller’s Earth

This valuable Earth is rather peculiar to Great Britain; it is, however said to be found in Saxony, Alsace, and Sweden. Hampshire and Bedfordshire are the only two places mentioned in England by most authors. Dr, Thomson says, “It occurs in greatest perfection in the South of England.” I, however, cannot find out that any has been discovered in Hampshire; and indeed the analysis usually quoted from Bergman does not appear to me to indicate Fuller’s Earth^*. His Grace the Duke of Bedford was so good as to supply me with an excellent specimen from Aspley; and I have seen the pits in Surry and Kent. A son is also found in Nottinghamshire, I exhibit a small piece from Aspley, as above: it is the lightest and softest in my possession, and has a character peculiar to the best for use, viz. a semi- transparency at the edges, even when dry, as I figure it. The lower specimen came from Nutfield in Surry, which is less transparent at the edges when dry, and is darker coloured, especially when in the pit, where it is called blue, in a manner synonymous with Blue Clay^†. I have a Sandstone from the bottom of the Bedfordshire pit, which has dark-green particles of Chlorite, such as is found in Cambridgeshire, and in the Irish Mulatto-Stone. I am told that under a surface of about six feet there are several strata of whitish and reddish sand, under which is a stratum of Sandstone, then a sandy Fuller’s Earth, called Cledge, which is thrown away; and that the proper Fuller’s Earth is found at a depth of about 14 feet, when there is some redder Fuller’s Earth, called Crop; the lower half of the Stratum is called Wall-Earth, and is reddish: hut I suspect this must vary according to time and circumstances.

The Surry Fuller’s Earth is found at different depths, as from nine to twenty or thirty feet. At one place, upon a hill, the surface was a wood; and when I examined the Earth at the bottom of the plants, I found it full of semi-transparent waxy particles with common light earth, and some ferrugineous appearances: below this were different strata of small stones, lying tile-wise, being flattish, and some approaching Hornstone, with a ferruginous sand, and green Chlorite particles: these are alternate, two or three times, when larger and rounder stones succeed, which are often Seplaria, holding shells and petrified wood; under these are small or large stones, flat and squarish, some of three or four feet in thickness, and often arranged in a very orderly manner, with squared joints, like a castle-wall; between them are flat stalagmitical flakes, composed of rather porous and light Carbonate of Lime, looking like mortar, to help the deception. Often next to these are a few small flattish stones and a ferruginous Fuller’s Earth, which is sent to London for housewifery purposes. The Earth below this has a dark blueish slate colour for six or nine feet: this is brought out in lumps of from ten pounds to a hundred weight, carried to a shed to be weighed for sale, and in a few hours is placed in a waggon to send to be shipped near London Bridge for Yorkshire. It may be observed, that as it cracks in the pit by the access of the external air, the outsides of the lumps become more or less ochrey, as the second figure shows, and afterwards the whole bleaches, and we cannot blacken it again; for, if it be wetted, it becomes lighter still, and falls to pieces: this may-depend on the Oxide of Iron, and something carbonaceous. As the Spec. Grav. of Fuller’s Earth is about 2, it is a curious fact to understand that large masses of Sulphate of Barytes^‡ are found suspended in it j but of this more will be said hereafter.

Kentish Fuller’s Earth, tab. 232, upper figure, is found at present near Bersted, but not in abundance, like that of Nutfield, and is not above from three to six feet from the surface, under mixed sand, and differs also from that in being found with much water, and not being in large pieces, or above half a pound, as well as in requiring careful picking and washing j when it is laid out to dry, and then shedded for carting to the Med way. It is rather softer to the touch than the kind from Surry, but generally dries darker, and has a more ochraceous crust. The three sorts of which I have spoken have all a very similar fracture, perfectly conchoidal, with a reverse inclining to the letter S.

Nottingham Fuller’s Earth, lower figure, varies like the others, but is generally more opaque and soft, rather than waxy, in appearance. What has been sent me evinces the admirable contrivance of Nature. The former varieties were infiltrated through sand and between stones, whereas this is preserved, as it were, in large nodules of red clayey Sandstone, and is thus as effectually distinguished as the kernel of a nut, I understand these are found in sandy rocks, and that women and children strip the Fuller’s Earth of its coloured covering.

This earth is met with in other places, but I believe not in sufficient quantities for market.

These specimens of this substance, from what I can judge of them without analysis, are of the best sort, and should seem to contain much Magnesia. Its waxy, soft, or unctuous appearance would indicate it to be a Steatite Clay, and us greenish hue certainly bespeaks the presence of Talc or Chlorite, which is so well incorporated with it as to seem to help its granular texture. In fine, it appears a more de composed state of Steatite, like many of the neighbouring stones; some having the whole composition, yet being in the form of a granular stone; vtz t whitish Steatite, green granular Chlorite, Silex, and Clay. Some of the stones found above it are coated with this, and are Flint, or Flinty Hornstone, within.

Fuller’s Earth is more or less massive, dull, somewhat granular. It does not soil the fingers, and may be polished by handling, though more by the finger nail; particles in grains, and on the edges, often admitting light, give it a waxy transparency. It feels soft and greasy, is easily scratched by the finger nail, cracks irregularly on drying; fracture large or small, conchoidal, deep, zigzag, sharp and angular, sometimes broad and plated; roughens by wetting, scarcely adheres to the tongue, becomes lighter on drying, but If pressed before it be dry, nearly retains its original colour; falls gently to powder in water, where it feels soft, and does not stick to the fingers.—Colour light-brown to dark-greenish brown, uniformly of one tint, or rather accidentally spotted, striped and clouded, sometimes with talcose particles glistening in it. For sale it is generally chosen as nearly uniform as possible.

As there appears to be some confusion among the authors I have looked at for this Earthy I have thought it the more necessary to be thus particular.

Mr. Hatchett once intended to examine the Fuller’s Earth chemically, and made much inquiry about it, but we have to regret that he did not complete his experiments. He informs me that he knew of none from Hampshire, and that he believed Bergman and others had been led into a mistake.