320 Mr. Hatchett's Analysis of 
heat, I removed it,' and found the residuum to be a black 
blistered matter. 
I then examined the sulphureous acid and sulphate of am- 
moniac which had risen, but did not find any trace of molyb- 
daena. 
I next poured nitric acid diluted with an equal weight of 
distilled water on the black residuum in the retort, and dis- 
tilled it. 
As soon as the acid began to be warm, nitrous fumes were 
discharged, and when the distillation had been repeated with 
a second portion of nitric acid, I found the whole of the black 
matter converted into a pale citron-coloured substance, which 
was the molybdic acid. 
I shall not here mention the experiments made on this acid, 
but shall speak of them after I have given an account of the 
analysis of the molybdate of lead, which I immediately at- 
tempted, according to the method pointed out by the fore- 
going experiments. 
§ XI. Analysis of the Molybdate of Lead. 
I put 230 grains of the purified ore reduced to a fine pow- 
der into a glass matrass, and having poured on it one ounce 
of concentrated sulphuric acid, I digested it in a strong heat 
during an hour. 
When the solution was become cool and had settled, the 
^cid was cautiously decanted from the powder, and distilled 
water was poured on till it came away tasteless. 
The same operation was repeated twice, so that three 
ounces of sulphuric acid were used. 
