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H2O (combined)

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Originally appearing in Volume V11, Page 298 of the 1911 Encyclopedia Britannica.
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H2O (combined). . 13.19 Ioo.o5 (Analysis by P. G. Sanford, Geol. Mag., 1889, 6, pp. 456, 526.) Of other published analyses, not a few show a lower silica content (44 %, 50 %), along with a higher proportion of alumina (11 %, 23 %). Fuller's earth may occur on any geological horizon; at Nutfield in Surrey, England, it is in the Cretaceous formations; at Midford near Bath it is of Jurassic age; at Bala, North Wales, it occurs in Ordovician strata; in Saxony it appears to be the decomposition product of a diabasic rock. In America it is found in California in rocks ranging from Cretaceous to Pleisto fene age; in S. Dakota, Custer county and elsewhere a yellow, gritty earth of Jurassic age is worked; in Florida and Georgia occurs a brittle, whitish earth of Oligocene age. Other deposits are worked in Arkansas, Texas, Colorado, Massachusetts and South Carolina. Fuller's earth is either mined or dug in the open according to local circumstances. It is then dried in the sun or by artificial heat and transported in small lumps in sacks. In other cases it is ground to a fine powder after being dried; or it is first roughly ground and made into a slurry with water, which is allowed to carry off the finer from the coarser particles and deposit them in a creamy state in suitable tanks. After consolidation this fine material is dried artificially on drying floors, broken into lumps, and packed for transport. The use of fuller's earth for cleansing wool and cloth has greatly decreased, but the demand for the material is as great or greater than it ever was. It is now used very largely in the filtration of mineral oils, and also for decolourizing certain vegetable oils. It is employed in the formation of certain soaps and cleansing preparations. The term " Fuller's Earth " has a special significance in geology, for it was applied by W. Smith in 1799 to certain clays in the neighbourhood of Bath, and the use of the expression is still retained by English geologists, either in this form or in the generalized " Fullonian." The Fullonian lies at the base of the Great Oolite or Bathonian series, but its palaeontological characters place it between that series and the underlying Inferior Oolite. The zonal fossils are Perisphinctes arbustigerus and Macrocephalus subcontractus with Ostrea acuminate, Rhynchonella concinna and Goniomya angulifera. The formation is in part the equivalent of the " Vesulien" of J. Marcou (Vesoul in Haute-Saone). In Dorsetshire and Somersetshire, where it is best developed, it is represented by an Upper Fuller's Earth Clay, the Fuller's Earth Rock (an impersistent earthy limestone, usually fossiliferous), and the Lower Fuller's Earth Clay. Commercial fuller's earth has been obtained only from the Upper Clay. In eastern Gloucestershire and northern Oxfordshire the Fuller's Earth passes downwards without break into the Inferior Oolite; northward it dies out about Chipping Norton in Oxfordshire and passes laterally into the Stonesfield Slates series; in the midland counties it may perhaps be represented by the " Upper Estuarine Series." In parts of Dorsetshire the clays have been used for brickmaking and the limestone (rock) for local buildings. See H. B. Woodward, " Jurassic Rocks of Great Britain," vol. iv. (1894), Mem. Geol. Survey (London). [J. A. H.]
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