Experiment Station Record, Volume 39, July-December, 1918 Page: 12
xxix, 1002 p. ; 24 cm.View a full description of this book.
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12 EXPERIMENT STATION RECORD. [Vol. 39
determination of organic matter can be removed by successive digestions with
a 1 per cent acid solution containing 0.5 per cent each of hydrochloric and
hydrofluoric acids without decomposing or dissolving more than a slight amount
of organic matter. The procedure is as follows:
A 1 gim. sample is digested twice with 50 cc. of water for five minutes on a
boiling water bath or at 85 C. and decanted through a Gooch crucible, using
suction. The extract is transferred to beakers and concentrated to a few cubic
centimeters. The residue is digested six times with 10 cc. of 2.5 per cent hydrochloric
acid, 10 cc. of 2.5 per cent hydrofluoric acid, and 30 cc. of water. After
washing with water, the residue is transferred to a small dish and the concentrated
water extract added. After drying to constant weight at 100, the
residue is ignited and the total organic matter calculated from loss on ignition.
A more rapid and in most cases quite as satisfactory method omits the water
extraction, disregarding the possible water-soluble organic matter in the soil
since duplicate analyses have shown that, except in the case of some soils very
rich in organic matter, the results in both methods are practically the same.
The investigation includes results of examination of the effect of the acid
reagent on hydrated and unhydrated minerals, on the mineral matter in different
kinds of soil, on the loss on ignition and on the organic carbon in the
soil. A table is given of the analyses of 25 varieties of soils for organic matter
by the two methods outlined above and by the older organic carbon and losson-ignition
methods.
The author believes " that the method for the determination of organic matter
outlined in this paper eliminates the errors in the loss-on-ignition method
due to hydrated minerals and carbonates and probably to unoxidized minerals,
and that it is superior to the organic carbon method for the determination of
organic matter in soils."
The volumetric determination of sulphates in water extracts of soils,
A. W. CHRISTIE and J. C. MARTIN (Soil Sci., 4 (1917), No. 6, pp. 477-479).--
The volumetric method for the estimation of small amounts of sulphate in the
urine by titration of the precipitated benzidin sulphate with potassium permanganate,
as described by Raiziss and Dubin (E. S. R., 33, p. 415), has been
adapted by the authors at the California Experiment Station to the determination
of small amounts of water-soluble sulphates in soil. In the final titration
N
0 potassium permanganate is used, 1 cc. of which is calculated to equal
0.15 mg. S04. Care should be taken in the washing of the precipitate, as if
less than 15 cc. of wash water is used high results are obtained, indicating
that the excess reagent has not been entirely removed, while with more than
20 cc. low results are obtained, due to the slight solubility of benzidin sulphate.
The accuracy of the method has been tested with sulphate solutions of known
concentration and with a typical 1: 5 soil extract. The method has an average
error of 3 per cent and is believed to be superior to colorimetric or nephelometric
methods, especially for small amounts of sulphate.
A study of the De Roode method for the determination of potash in fertilizer
materials, T. E. KEITT and H. E. SHIVEr (Jour. I. Inds and Engin.
Chem., 10 (1918), No. 3, pp. 210-222; abs. in Chelt. Abs., 12 (1918), No. 10, pp.
1095, 1096).-The author reports results obtained at the South Carolina Experiment
Station for the determination of potash in fertilizer materials by the
method proposed by De Roode (E. S.L., 6, p. 867) and later by Moore (E. S. R.,
10, p. 408). The method, which is applicable to all commercial fertilizers, including
salts, is described in detail, and analyses are reported of samples of
commercial fertilizers and various synthetic solutions of known composition
by the modified De Roode and the official Lindo-Gladding method,
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General Index to Experiment Station Record, Volumes 26-40, 1912-1919 (Book)
A topical, alphabetically arranged index to volumes 26-40 including experiment station records, publications reviewed, and foreign publications. In has a 'Consolidated Table of Contents' which lists all editorial notes and publications of the experiment stations and Department of Agriculture from the referenced volumes.
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United States. Office of Experiment Stations. Experiment Station Record, Volume 39, July-December, 1918, book, 1919; Washington D.C.. (https://digital.library.unt.edu/ark:/67531/metadc5015/m1/41/: accessed March 28, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.