The mineral molybdenite, MoS2, is described2 as occurring in hexagonal crystals with a very complete basal cleavage. A study of its crystal structure has been carried out using X-ray spectral photographs and Laue photographs treated as previously described.3 Since the crystals bend very

2.The reaction is explained, after the suggestion of Freundlich and Nathansohn, as one of a 2-stage photochemical oxidation of hydrogen sulfide to colloidal sulfur and a thionic acid, accompanied by reaction between hydrogen sulfide and the thionic acid which serve as stabilizing electrolytes for micelles of arsenic trisulfide and sulfur, respectively. Removal of the stabilizing electrolytes produces destabilization of the 2 colloids which are consequently precipitated. The increase in conductivity is explained as due to the building up of a concentration of the thionic acid sufficient to serve as the stabilizing electrolyte for the colloidal sulfur, the reaction between hydrogen sulfide and the thionic acid then proceeding a t such a rate that the equilibrium is maintained between the several components of the system, further change in the conductance thus being prevented.

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The maximum temperature at which molybdenum trioxide can be safely ignited without fear of appreciable loss by volatilization has been established as approximately 600°.Conditions and apparatus for accurately and conveniently converting molybdenum trisulfide to trioxide have been described.The use of oxidizing agents to aid the conversion of the sulfide to oxide is unnecessary.

The evidence thus obtained leads us to conclude that element 87 occurs in samarskite. Furthermore, this element yields a chloride volatilizable at 1000°, and its alum is the least soluble in the alkali series. A name for the element will not be announced until additional confirmatory data are obtained.