C 285 3 
XII. An Analysis of the Carinthian Molybdate of Lead ; with 
Experiments on the Molybdic Acid. To which are added 
some Experiments and Observations on the Decomposition of 
the Sulphate of Ammoniac. By Charles Hatchett, Esq. 
Communicated by Sir Joseph Banks, Bart. K. B. P.R.S. 
Read April 14, 1796. 
SI- 
TE he celebrated Scheele, in 1778, read before the Academy 
of Sciences at Stockholm an essay, in which he proved, by a 
series of ingenious experiments, that the. mineral called Mo- 
lybdcena was composed of sulphur, and a peculiar metallic sub- 
stance, which, like arsenic and tungsten, was liable by super- 
oxygenation to be converted into a metallic acid, which in its 
properties differed from any other that had been previously 
discovered.* 
The experiments of M. Pelletier, - f Mr. Islmann,J 
and Mr. Hielm,§ confirmed the discovery of the Swedish 
chemist ; but the existence of this metallic substance was only 
known to be in that mineral which Scheele had examined, as 
no vestige of it had as yet been discovered in other bodies ap- 
* Scheele’s Essays, translated by Dr. Beddoes, p. 227. 
f Journ. de Physique, Decembre, 1785. 
J Cbemiscbe Annalen von Crell, 1787, et Journ. de Physique, Oclobre, 1788. 
§ Journ. de Physique, Mai, 1789. 
