The composition and determination of cerium oxalate / by Frederick B. Power and Frank Shedden.

  • Frederick Belding Power
Date:
[1900]
Catalogue details

Licence: In copyright

Credit: The composition and determination of cerium oxalate / by Frederick B. Power and Frank Shedden. Source: Wellcome Collection.

    6/24 (page 4)
    100° C. (found 19* 14 per cent., calculated 19*23 per cent.), and also that it was found to contain 38*89 per cent, of cerium, calculated 39*31 per cent. The latter result agrees, however, closely with a salt containing 10 molecules oi water, which requires 38*6 per cent, cerium. In connection with the formula for cerium oxalate, Beilstein also refers to Erk (Zeits. fur Chemie, N. F. 1871, 7, HI) abstiacted in J. Chem. Soc. 24, 494. In his paper, Erk remarks that the amount of water in the salt has been variously determined by different investigators. Rammelsberg (Pogg. Ann. 108,44), for example, determined the “ carefully dried ” cerium oxalate as CeC204.3H20, and Kjerulf (Ann. Chem. Pharm. 87, 12) gave it the formula CeC204.H20, although neither of them stated the tem¬ perature at which they dried the oxalate. Gibbs (Zeits. fur Chemie, N.F. 1, 15) regarded the mixed oxalates of cerium, lanthanum, and didymium as corresponding to the formula CeC204.3H20, and employed this formula in his quantitative determinations of cerium. Erk himself considered the air-dried salt to have the formulaCeC204.4H20, and that 3 molecules of water were lost at 100° C., while the last molecule could not be expelled without the decomposition of the salt. He also states that, in its composition and behaviour on heating, cerium oxalate corresponds entirely to didymium oxalate. In all of these formulas cerium was regarded as bivalent, and as Erk used the atomic weight of 89 for cerium, his formula would require to he multiplied by three in order to make it comparable with that now accepted for cerium oxalate. His formula would thus become Ce2(C204)3.12H20 where Ce = 140. Brauner (Chem. News, 1895, 71, 284), whose excellent work on the rare earths is well known, refers indirectly to the estimation of the water in cerium oxalate for the purpose of checking other determinations, but he does not note the result of this estimation nor the formula for the salt. The Commission of the German Chemical Society have adopted the atomic weight of cerium as 140, which is in accordance with Brauner’s investigations (loc. cit.), and this has been more recently confirmed by Muthmann (Ber. 1898, 31, 1835) for CeCl^ by the ebuliioscope method. We have employed this atomic weight for our calculations in the analysis of cerium oxalate. The views regarding the composition of cerium oxalate have been considered somewhat in detail, as they naturally have an important bearing upon the analysis of the salt, and especially, as we shall show later on, that we believe the accepted formula of the salt, with regard to the amount of water, to be not quite correct.