An investigation of the silica deposits of southern Illinois . eposits upon thestfindard cones. In all cases they were darkened by the carbon, which penetratedhaJf way into the cone. The test cones of silica in each case although made upv/ith a carbonaceous binder v/ere the natural color of the rav/ material. Thiswas noticed in the tests in which the heating was stopped before the softeningpoint of the test cones or standard cones was reached. No suitable explanationof this could be offered. Washing Tests:- This test was tried v/ith the gannister with the view ofremoving some of the impurities
An investigation of the silica deposits of southern Illinois . eposits upon thestfindard cones. In all cases they were darkened by the carbon, which penetratedhaJf way into the cone. The test cones of silica in each case although made upv/ith a carbonaceous binder v/ere the natural color of the rav/ material. Thiswas noticed in the tests in which the heating was stopped before the softeningpoint of the test cones or standard cones was reached. No suitable explanationof this could be offered. Washing Tests:- This test was tried v/ith the gannister with the view ofremoving some of the impurities also of detei-nining the character of thefiner particles, which were too to distinguish under the microscope. Thefollowing method was employed. Ten gram lots (dried at 110°C) of each sample of gannister were shakenin distilled water with 0*01% of Na2C02(which was found to produce the greatestdegree of defloculation), for eight hours. After this period the samples wereallowed to stand for tv/o hours and then the water decpjited from the settled. 13. material and allov/ed to stand for twelve hours longer. At the end of this timeit was again decanted from the settled material. At the end of thirty-six hoursthe water from the second decantation remained turbid with practically no sett-ling. The suspended material was nade tc settle out by acidifying the waterwith a few drops of HCL. Each residue obtained from decanting was subjected totwo shakings and decantations similar to the first one. The resulting residueswere washed well and dried. The test is somewhat crude but shows the possibil-ities well enough. Each residue was v/eighed, the silica content deterained, (thus giving theimpurities left by difference), exainined under a microscope and the first residuegiven another fusion test. The follov/ing are resvilte obtained. Samrile 1847 - Gannister Portion 1st Residue Nature of % inMaterial residue Chert ^ 2nd Residue Too small to ^be determined Residue Sett-le
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectminesandmineralresou
