ABRASIVE MAPE~RIALS 1341

at $4,377,353; and 1933—35: 244,342 tons valued at $3,618,428. Sales
during 1941 were at a considerably higher level than in prior years.
 California and Oregon remained the principal producing States; other States
in which diatomaceous earth was produced in 1941 were Florida, Idaho, Nevada,
New Mexico, New York, and Washington (see fig. 1).
 Although new uses constantly are being developed, the chief mar.' keting
outlets for diatomite are as ifiter aids; as polish ingredient, especially
silver polish; as an insulating material, either in board or as block; and
as fillers or adniixtures in a variety of products. The diatomaceous earth
operations of the Dicaiite Co. in Oregon were reported by Manning, who outlined
the equipment and processes
employed in treatment as well as the uses for which the finished prod.' uct
is adapted. The winning of commercial diatomite from freshwater bog deposits
in Florida, the various grades marketed, and the. uses of each type were
described.5
 Quotations on diatomite, as reported in Engineering and Mining Journal Metal
and Mineral Markets, remained unchanged throughout 1941, as follows: Crude
dried diatomite f. o. b. mines (Nevada), in bulk $7 per ton, in bags $12;
low-temperature insulation, $19 per ton; high-temperature insulation $40.
 The properties of diatomaceous earth and its uses as a filtering medium,
a carrier for catalysts, and a filler, and in the plastics and papermaking
industries were discussed by. Hall.6 The effect of chlorine on diatomaceous
earth was studied in Great Britain.7 Using a process developed by the Bureau
of Mines,8 a pilot-plant run on a Maryland diatomite was made to ascertain
operating costs and to determine the feasibility of producing this material
on a commercial scale.9
 Use of cliatomaceous earth instead of ifint in five different .types of
ceramic glazes resulted in improved gloss and an off-white color, according
to Keith.1° Diatomite as a base for chemical pigments" and its use in
the match 12 were described.
 Diatomaceous silica, also known as ldeselguhr, was first used in the sugar
industry in the United States about' 25 years ago. GraduaMy increased numbers
of units of modern ifitration equipment were installed, especially after
the introduction of. faster-flowing fflter aids in 1923. By 1930 filter aids
of diatomaceous earth were being used by nearly all sugar refineries in the
United States and Canada
 ' Manning, Paul D. V., Products from Diatoms: Chem. and Met. Eng., vol.
48, No. 9, September 1941, pp. 114—115.
 ' Pit and Quarry, Florida Bog Supplies Material Yielding Commercial Diatomite:
December 1941, pp. 48-49.
 ' Hall, Howard W., Diatomaceous Silica—How It Serves Industry: Pacific
Pulp and Paper md., vol. 15, April 1941, pp. 50-53; Chem. Abs., vol. 35,
No. 19, October 10, 1941, p. 6743.
 ' Barrett, L. R., Richardson, H. M., and Green, A. P., Action of Chlorine
on Refractory Materials. 111.—Diatomaceous Earth: Bull. British Refractory
Research Assc., No. 57, 1940, p. 19; Ceram. Abs (Am. Ceram. Soc.), vol. 21,
No. 1, January 1942, p. 13.
 ' Norman, James, and Ralston, Oliver, Purification of Diatomite by Froth
Flotation: Am. Inst. Mm. and Met. Eng. Tech. Pub. 1198, New York, 1940, 11
pp.; Mm. Technol., vol. 4, No. 3, May 1940.
 *Raiston, Oliver C., and Stern, A. George, Report of the Nonmetals Division,
Fiscal Year 1941: Bureau of Mines Rept. of Investigations 3599, 1941, p.
23.
 "Keith, Wendell P., Comparison of Flint awl Diatomite as a Source of Silica
in Ceramic Glazes; 44th Annual Meeting, Am. Ceram. Soc., April 19-23, 1942;
abs. Bull. Am. Ceram. Soc., vol. 21, No. 4, April 15, 1942, p. 18.
Il-Bijrwefl, E. C., Dlatomaceous Earth Base for Chemical Pigments: md. and
Eng. Chem., hid, ad., vol. 33, No. 7, July 1941, pp. 915-918.
"Crass, M. F., Jr., The Match Industry; Raw Materials Employed: Chem. md.,
voL 48, No.4, April 1941, pp. 424-433.