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Dewar and Scott write: 'Our attention has been directed for some time to a new determination of the atomic weight of manganese. This communication gives a succinct account of the results of the preliminary stages of such an inquiry, and although the further progress of the investigation may reveal some errors, still we feel convinced the final numbers can in no way differ materially from the present values, and therefore further delay in publication is unnecessary. The atomic weight of manganese has been determined by many chemists, but the resulting values vary considerably according to the special method selected. The results of the different investigators may be divided into two classes—those giving approximately 55 as the number, and those making it about 54. To the former class belong Turner, Berzelius, and Dumas, all of whom use the same method, viz., the determination of the silver chloride yielded by a weighed amount of chloride of manganese. Turner also made determinations from the analysis of the carbonate, and from the conversion of the monoxide into sulphate. Von Hauer used the same method as that employed by him in the determination of the atomic weight of cadmium, viz., the reduction of manganous sulphate to sulphide by ignition in a current of sulphuretted hydrogen. It is probable that this method is not very trustworthy, as, according to Schneider, the sulphide may be contaminated by oxysulphide. Schneider and Rawack belong to the second class of observers, the former employing the oxalate, and from its analysis calculating the atomic weight by deducting the weight of water and carbon dioxide obtained. Rawack, whose experiments were conducted in Schneider’s laboratory, weighed the water obtained by reducing manganoso-manganic oxide to manganous oxide.'

Annotations in ink.

Subject: Chemistry

Received 9 February 1883. Read 15 February 1883.

A version of this paper was published in volume 35 of the Proceedings of the Royal Society as 'On the atomic weight of manganese'.

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James Dewar

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Alexander Scott

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James Dewar, Alexander Scott, Paper, 'On the atomic weight of manganese' by James Dewar and Alexander Scott, 1883, PP/3/6, The Royal Society Archives, London,, accessed on 29 May 2024

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  • Proceedings Papers

    Dates: 1882 - 1894

    The archival collection known as 'Proceedings Papers' is comprised of manuscripts and occasional proofs of scientific papers sent to the Royal Society which were read before meetings of Fellows and printed in full in the Proceedings of the Royal Society.

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