Schaller — Chemical Composition of Molyhdic Ocher. 303 



acid, but the first two salts are probably hydrated ferric molyb- 

 dates. It is the writer's intention to continue the study of the 

 artificial formation of these salts, especially to obtain, in a state 

 of purity, that one which corresponds in composition to the 

 natural mineral. 



Occurrence of natural Mo O s .~- The existence of the trioxide 

 of molybdenum as a natural mineral has not been demonstrated, 

 and what is commonly believed to be Mo0 3 is shown to be a 

 hydrated ferric molybdate, Fe 2 3 .3Mo0 3 .7|-II 2 0. There is also 

 the possibility that thehyclrous oxide Mo0 3 .2H 2 0, or molybdic 

 acid, has a natural occurrence. If either of these should be 

 shown to exist, the name molybdite should be applied to the 

 species and the salt Fe 2 3 .3Mo0 3 .7^H 2 should receive a 

 different name ; but until it is shown conclusively that an oxide 

 of molybdenum does exist in nature, the name molybdite must 

 be retained for the hydrated ferric molybdate. 



