33^ Mr. Hatchett's Analysis of 
When the sulphuric and muriatic solutions of the molybdic 
acid are saturated with ammoniac, triple salts are formed, 
which are different in their properties from those which have 
been described ; for the triple salts produced by ammoniac are 
permanent, and do not appear to be decomposed by evaporation. 
If iron is present in the acid solution (sufficiently diluted), 
it is precipitated by ammoniac free from molybdic acid, espe- 
cially when the menstruum is the sulphuric acid. 
The affinity of the molybdic acid with muriate of ammoniac is 
so great, that by sublimation it even in part quits lead to unite 
with it, and then forms the blue triple salt, from which the 
blue oxyde does not separate, but in proportion that it is de- 
prived of oxygen by the gradual decomposition of the ammo- 
niac caused by repeated sublimations. 
When the sulphuric solution saturated with ammoniac is 
evaporated to a proper degree, the triple salt crystallizes in 
the usual figure of the sulphate of ammoniac, but the colour 
is bluish green. If, however, the evaporation is continued to 
dryness, a pale greyish-blue salt is left, and by distillation this 
salt is decomposed (after the manner of the decomposition 
which I have noticed in the sulphate of ammoniac), and the 
molybdaena remains in the form of a black powder, deprived 
of oxygen. 
I think it necessary here to observe, that when molybdaena 
is not in the metallic state, it appears to me to suffer four 
degrees of oxygenation. The first is the black oxyde ; the se- 
cond is the blue oxyde ; the third is the green oxyde, which 
(as it seems to be intermediate between an oxyde and an acid) 
I am inclined to call molybdous acid, according to the dis- 
tinction made by the new Nomenclature ; the last and fourth 
