FIGVEE 1.—Geographical distribution of diatomite and tripoli mines
in the United States.
1342
MINERALS YEARBOOK, 1941


and by many refineries and other types of sugar factories in different countries,'3
particularly beet-sugar factories. Methods and equip— ment have frequently
been developed and improved. Use, equipment, modem procedures, and the results
obtained in sugar refineries by diatomaceous earth filter techmque were discussed
in a series of articles in the techmcal press 14
 Tripoli —The total quantity of tripoli (including Pennsylvama rottenstoñe)
sold was slightly less in 1941 than in 1940—29,301 short tons compared
with 30,212 tons; the value of sales, however, rose 15 percent to $421,746
from $366,569 in 1940 Tripoli or amorphous silica was produced in the same
States as in 1940, the output coming largely from Illinois, Missouri, and
Oklahoma, other States reporting production were Arkansas, California, Pennsylvama
(rottenstone), and Texas
 According to Engine~ring and Mining Journal Metal and Mineral Markets, prices
of tripoli remained constant during 1941, as follows ' ~:
Once-ground through 40-mesh, rose- and cream-colored, $14.50; double-ground
through 110-mesh, rose and cream, $16; air-floated through 200-mesh, $26.
"Elsenbast, A. S., and Morris, D. C., Diatomaceous Silica Filter-Aid Clarification:
md. and Eng. Chem., md. ed., vol. 34, No. 4, April 1942, pp. 412-418.
14 Cummins, A. B., and Waymouth, C. E., Filtration of Sugar Solutions; Some
Factors Determined by Laboratory Test Procedures: md. and Eng. Chem., in
ed., vol. 34, No. 4, April 1912, pp. 392-398.
Cuniniins, A. B., Calcium Phosphates in the Filtration of Sugar Liquors:
md, and Eng. Chem., hid. ed., vol. 34, No. 4, April 1942, pp. 398-402; Clarifying
Efficiency of Diatomaceous Filter-Aids: md. and Eng. Chem., hid. ed., vo1.~
34, No. 4, April 1942, pp. 403-411.
Elsenbast, A. S., and Morris, D. C., Work cited in footnote 13.
"Quotations are per ton f. o. b. Missouri, in burlap bags, with paper liners,
minimum carload, 30 tons.