30 6 Mr. Hatchett's Analysis of 
remainder of the tube was filled with a hard greyish-blue 
salt. In the retort was a black pulverulent residuum. 
I collected all of the blue salt, and again sublimed it, and 
again obtained muriatic acid, blue salt, and some of the blaek 
powder. 
The blue salt was composed of muriate of ammoniac com- 
bined with the acid, or rather with a blue oxyde of molybdeena. 
H. The black residuum was put into a glass retort, and 
some nitric acid being poured on it, it was exposed to a mo- 
derate heat. Nitrous fumes were discharged, and when the 
distillation had been repeated, I found the whole of this black 
powder converted into the citron-coloured molybdic acid. 
I had evident proof that in this experiment a portion of the 
muriate of ammoniac was decomposed by each sublimation, 
and also that part of the molybdic acid was deprived of oxy- 
gen, and remained in the retort, if not in the state of metal, 
at least combined with so small a quantity of oxygen as to be 
nearly approaching to it.* 
Molybdate of Lead with Muriatic Acid. 
EXPERIMENT II. 
One drachm of the ore was digested with muriatic acid, and 
distilled water was added till the whole was dissolved, except- 
ing a small residuum of siliceous earth. 
The solution was filtrated, and was repeatedly evaporated, 
till muriate of lead was no longer separated. 
* A black powder of a similar nature appears to have been obtained by Scheele, 
when he distilled the white molybdic acid with a small quantity of olive oil. Essays, 
p. 238. 
