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A new apparatus for the determination of carbon dioxide
Published online by Cambridge University Press: 14 March 2018
Extract
As most analysts recognize, the method generally used for the determination of carbon dioxide present as carbonate, by decomposition with acid, absorption in soda-lime or soda-asbestos, and weighing as carbon dioxide, is open to several objections; and several suggestions have been made from time to time with the object of avoiding the use of absorption tubes, but none of these have come into general use, generally because of inconvenience in manipulation.
The principal objection to the use of absorption tubes (apart from their general inconvenience and the numerous precautions their use entails) lies in the uncertainty of the blank correction; when a blank experiment is performed, under precisely the same conditions as the actual determination, a small gain in weight of the absorption tubes is almost invariably observed, but in a series of several blank experiments, this gain is frequently very variable, and by no means proportional to the volume of air drawn through the absorbers, unless many precautions are observed.
- Type
- Research Article
- Information
- Mineralogical magazine and journal of the Mineralogical Society , Volume 24 , Issue 149 , June 1935 , pp. 76 - 83
- Copyright
- Copyright © The Mineralogical Society of Great Britain and Ireland 1935
References
page 76 note 1 See, for example, the procedures referred to by Hillebrand, W. F. and Lundell, G. E. F., Applied inorganic analysis. New York, 1929, p. 631 Google Scholar, section D.
page 76 note 2 Especially if soda-lime is used; ghis absorbent does not function efficiently if it is too dry.
page 77 note 1 See, for example, Manley, J. J., in Sir Edward Thorpe, Dictionary of applied chemistry. London, 1921, vol. 1, pp. 521-522Google Scholar, sections 12 and 13.
page 76 note 2 Sulphuric acid or sulphur trioxide may be present in the gas-stream if carbon is being determined by wet combustion; this will interfere in the first, but not in the second, procedure.
page 76 note 3 Except in the determination of free carbon or organic m~tter by direct combustion, should sulphides or sulphates be present.
page 78 note 1 Lindner, J., Zcits. Anal. Chem., 1933, vol. 95, p. 1.Google Scholar
page 78 note 2 The form of wash-bottle described by the author (Min. Mag., 1933, vol. 23, p. 386) is most convenient for this purpose, but the glass spiral must be omitted, as it ceases to function when the carbonate precipitate becomes bulky, and even leads to splashing and loss.
page 79 note 1 This should not contain more than about 0.10 to 0.15 gm. carbon dioxide, unless a larger wash-bottle is used at D.
page 80 note 1 It is solely for this reason that the wash-bottle D is interpolated to collect most of the CO2; if it is known that the material being used does not contain more than about 10 mg. of CO2, D may be omitted and the CO2 collected wholly in F, greatly simplifying the subsequent procedure.
page 81 note 1 Although the area of the glass filter-funnel F is as great as that of an absorption tube the errors due to absorbed air and moisture are much less, since tbe funnel is dried in an oven and cooled in a desiccator; if allowed to stand at least ¾ to 1 hour in the desiccator the weight of such a funnel remains constant to 0.1 or 0.2 mg. during several dryings and weighings. The effective error is further reduced by the large factor BaCO3 a or BaS04:CO2. But for the highest accuracy solution and precipitation as BaSO4 is probably preferable.
page 81 note 2 But little washing will be needed as there will be no foreign salts present.
page 81 note 3 Borgström, L. H., Zeits. Anal. Chem., 1914, vol. 53, p. 685.CrossRefGoogle Scholar
page 82 note 1 The purifying train normally used with the ahsorption-tube method cannot be relied on to trap HF.
page 82 note 1 Compare Reich-Rohrwig, W., Zeits. Anal. Chem., 1933, vol. 96, p. 315.CrossRefGoogle Scholar (Absorption tubes used.)
page 82 note 3 The experiments were carried out by Mr. S. E. Ellis of the Mineral Departmeat.