Abstract

Chemical analyses of nine samples of marl from lakes in Minnesota by conventional analytical procedures and by modified or rapid methods that make use of ethylenediamine tetraacetic acid, EDTA, are compared. The two procedures report the composition in somewhat different terms. In the rapid analysis, the sodium carbonate fusion for decomposition of the sample is eliminated. Insoluble material rather than SiO 2 is reported; Al 2 O 3 ,is replaced by a difference value, M 2 O 3 . Results for CaO, MgO, and CO 2 are comparable to the conventional gravimetric determinations. The Minnesota lake marl is composed chiefly of calcium carbonate with admixed silt, sand, and organic matter. The organic matter complicates the analytical procedures and is removed by ignition of the sample. Ferrous iron and total water cannot be determined. The analyzed samples range from 0.5 to 17% SiO 2 and from 31 to 51% CaO. The MgO content is small, ranging from 1.1 to 1.8%. The rapid analysis, although designed for Minnesota lake marl, can be applied to other carbonate materials. It has the advantage of permitting a large number of samples to be handled.

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