An analysis of the Carinthian molybdate of lead ... : To which are added some experiments and observations on the decomposition of the sulphate of ammoniac / [Charles Hatchett].

  • Hatchett, Charles, 1765?-1847
Date:
[1796]
Catalogue details

Licence: Public Domain Mark

Credit: An analysis of the Carinthian molybdate of lead ... : To which are added some experiments and observations on the decomposition of the sulphate of ammoniac / [Charles Hatchett]. Source: Wellcome Collection.

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    To corroborate this assertion, it will be proper to consider the effects of muriatic acid on that of molybdaena, especially as the affinity between the radical principle, or base of the mu¬ riatic acid, and oxygen is known to be so great, that no chemist has as yet been able to effect a separation of the con¬ stituent principles. It has been mentioned, that molybdic acid when dissolved in muriatic acid also parts with some oxygen, and tinges the menstruum with a green colour. But heat does not enable it to take back the oxygen, for it augments the effects of the muriatic acid, which, when distilled, passes oxygenated into the receiver, and the molybdic acid is converted into a bluish- grey oxyde.* These effects clearly prove, that heat in this case acts in¬ versely to what it did when the nitric and sulphuric acids were the menstrua. For then the increase of affinity was between molybdaena and oxygen, but here it is in favour of the base of muriatic acid ; so that by the continuation of heat, the muriatic acid carries with it into the receiver a certain portion of oxygen which it has taken from the molybdic acid, and the latter is left in the state of an oxyde. From this it appears that muriatic acid uniformly tends to deprive the molybdic acid of a certain quantity of oxygen, and that heat produces a contrary effect on this solution to that which it did on the one made with sulphuric acid; and heat and cold do not therefore produce a change of colour. I do not, however, believe that muriatic acid acts thus con¬ stantly on all of those metals which can be dissolved by it; on the contrary, there is a muriatic solution which much re- * Siemens d’Hist. Nat. et de Cbimie,par M. de Fqurcroy, Tome II. p. 439.