the Carinthian Molybdate of Lead. 317 
and the sulphureous acid also came over in the same manner 
as when only the sulphate of ammoniac was distilled. 
Lastly, I distilled one ounce of the sulphate of ammoniac 
with 20 grains of the yellow molybdic acid. During the dis- 
tillation, the ammoniac and sulphureous acid were produced in 
as great quantities as when the sulphate of ammoniac was dis- 
tilled by itself. But the molybdic acid remained in the retort, 
deprived of oxygen, in the form of a black blistered matter, 
which was again converted into the yellow acid when dis- 
tilled with nitric acid. 
From these experiments it appears, that the sulphate of am- 
moniac Is not (as many eminent chemists have imagined) in- 
capable of being decomposed without some intermediate sub- 
stance, but on the contrary, the whole of it can be raised, and 
a great part decomposed, whenever a proper degree of heat is 
applied ; for then a certain portion of ammoniac first comes 
over, so that the remainder is combined with acid in excess, 
and the hydrogen of the ammoniac which remains unites with 
part of the oxygen of the sulphuric acid, and forms water, 
which passes into the receiver, accompanied by the acid (now 
become sulphureous acid), and by the azote in the state of gas. 
Various methods have long been in use to decompose am- 
moniac. 
Metallic oxydes produce this effect ; and Scheele particu- 
larly mentions, that if arseniate of ammoniac is distilled, gas 
is produced, and the acid of arsenic is reduced to the metallic 
form, and as such is sublimed.* 
* Essays, page 155. The same effects also were produced when acid of arsenic, was 
sublimed with muriate of ammoniac, page 161. 
