3C2 Mr. Hatchett’s Analysis of 
acid, and afterwards obtained some Prussian blue by prussiate 
of pot-ash. 
B. The alkaline solution which had been formed when the 
melted mass was washed, was poured on a filter, and distilled 
water was added till it came away tasteless. 
The filtrated liquor was without colour : nitric acid was then 
added till the alkali was saturated. 
When about half of the requisite quantity of nitric acid was 
poured in, the liquor became pale blue, and as the quantity 
was increased it changed to green ; and, lastly, when the ni- 
tric acid was added till it was in a small excess, the liquor 
was of a bright amber colour. 
1. This solution, with prussiate of pot-ash, afforded a brown 
precipitate of molybdaena. 
2. Muriate of tin changed the colour to a beautiful deep 
blue. 
3. But sulphuric acid had not any effect. 
C. The amber-coloured solution was evaporated to dry- 
ness, and a saline mass of a bright citron colour remained at 
the bottom of the vessel. 
As part of the yellow colouring matter appeared to be only 
mixed with the salt, I dissolved it in distilled water, and se- 
parated a quantity of a citron-coloured powder, which was the 
molybdic acid. 
The solution was twice again evaporated, and each time 
some molybdic acid was separated ; but a part still remained 
intimately combined with the salt, so as with water always to 
produce the amber-coloured solution* 
* Although the solution at first afforded a brown precipitate with prussiate of pot- 
ash, yet when it had been twice evaporated, it required the addition of some nitric 
