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The determination of small amounts of copper in rocks
Published online by Cambridge University Press: 14 March 2018
Extract
In modern petrology increasing importance is being attached to the content of minor chemical constituents, the determination of which is now frequently required, whereas hitherto they have usually been disregarded. In consequence, methods for their accurate determination in small amount have not always been fully worked out. Copper is a case in point, and it is already clear that the method here advocated will show that this metal is much more widely distributed in rocks than is generally realized. Moreover, the use of a large sample, such as 20-50 grams, is no longer necessary.
In attempting to apply to rocks the very sensitive colorimetric method described by T. Callan and J. A. Russell Henderson, various difficulties were encountered, and modifications were developed whereby the method can be adapted to the determination of from 0·001-0·25 % of CuO in silicate rocks and minerals. The reagent used is sodium diethyl-dithio-carbamate, which gives a yellow colour with copper in slightly ammoniacal solution. The authors give a list of other metals which also give a coloration or turbidity with this reagent.
- Type
- Research Article
- Information
- Mineralogical magazine and journal of the Mineralogical Society , Volume 24 , Issue 148 , March 1935 , pp. 35 - 41
- Copyright
- Copyright © The Mineralogical Society of Great Britain and Ireland 1935
References
Page 35 Note 1 Callan, T. and Henderson, J. A. R., Analyst, London, 1929, vol. 54, p. 650.Google Scholar
Page 36 Note 1 Strafford, N., The detection and determination of small amounts of inorganic substances by colorimetric methods. London (Institute of Chemistry), 1933.Google Scholar
Page 36 Note 2 Hillebrand, W. F. and Lundell, G. E. F., Applied inorganic analysis. New York and London, 1929, p. 186.Google Scholar
Page 36 Note 3 If preferred, the decomposition may be effected by fusion, followed by a separation of silica, and then by the ammonia precipitations. It requires slightly more time in manipulations than the procedure here described. Moreover, the large amount of sodium chloride present causes some turbidity with the organic reagent.
Page 38 Note 1 W. F. Hillebrand and G. E. F. Lundell, loc. cit.., p. 70. Haddock, L. A. and Evers, N., Analyst, London, 1932, vol. 57, p. 495.Google Scholar
Page 39 Note 1 In the majority of cases 250 c.c. is the most suitable volume.
Page 39 Note 2 It has been found that this solution hydrolyses on keeping. It is best to prepare it freshly by dilution from a solution containing 0.0001 gm. Cu. This is prepared from A. R. copper sulphate and should contain a few drops of sulphuric acid.