3°8 
Mr. Hatchett’s Analysis of 
§ X. Molybdate of Lead with Sulphuric Acid. 
From the experiments of Mr. Klaproth it appears, that 
he only employed nitric and muriatic acid ; and on this ac- 
count I was desirous to try the effects of sulphuric acid, espe- 
cially as Scheele has proved that it is able to dissolve a con- 
siderable quantity of the acid of molybdsena * Moreover, I 
conceived hopes of success, on the supposition that the elec- 
tive attraction between lead and sulphuric acid was more 
powerful than that between lead and molybdic acid ; and as sul- 
phate of lead is nearly insoluble, I should thus be able to make 
a complete separation of the constituent parts of the ore, I 
therefore made the following experiment. 
120 Grains of the purified ore in fine powder were put into 
a small glass matrass, and one ounce of concentrated sulphuric 
acid was poured on the powder. 
The matrass was then placed over an Argand lamp, and 
the acid was boiled during an hour. The ore became white, 
and the acid was of a beautiful blue. 
When it had stood some hours, I poured the acid into ano- 
ther vessel, edulcorated the powder with distilled water, and 
added the washings to the acid solution. 
Another ounce of sulphuric acid was poured on the powder, 
and boiled as before. It was faintly tinged with blue ; and I 
added it to the first solution, as well as the water with which 
the powder was washed. 
That I might not leave any part of the molybdic acid un- 
extracted, I repeated the operation a third time. The powder 
Essays, p. 235. 
