the Carinthian Molybdate of Lead. 321 
The acid solutions and washings were then filtrated, and 
were received in a large glass vessel. 
I diluted the pale blue liquor with distilled water, in the 
proportion of sixteen to one, and afterwards gradually added 
ammoniac, until it was completely saturated. The liquor 
then became deep blue, and appeared turbid. 
When it had stood about 24 hours, a loose pale ochry pre- 
cipitate subsided, and was collected on a filter, the weight of 
which had been noted * 
This precipitate was edulcorated, and afterwards dried with 
the filter on the flat top of a tin vessel heated by boiling wa- 
ter, after which the weight of the precipitate was 4.2 grains. 
The colour of the dry precipitate was yellowish brown, and 
when dissolved in muriatic acid it was precipitated by prussiate 
of pot-ash in the state of Prussian blue. 
I now poured part of the clear blue solution, which was com- 
posed of sulphuric and molybdic acid saturated with ammoniac, 
into a glass retort, and when about half was evaporated, I con- 
tinued to add the remainder of the liquor at different times till 
the whole was become a concrete salt. 
I then raised the fire and continued the distillation until all 
of the sulphate of ammoniac was decomposed or driven over ; 
but as some of the sublimed salt was fixed in the neck of the 
* This is one of the many instances which prove the weak affinity between molyb- 
dsena and oxygen ; for it is well known that pure ammoniac precipitates iron from 
sulphuric acid, in a state nearly similar to martial ethiops ; but in the present case 
the iron takes a considerable portion of oxygen from the molybdic acid at the moment 
that the acid menstruum is saturated by the ammoniac, and it is therefore precipitated 
in the form of a yellowish-brown oxyde, whilst the molybdic acid being thus deprived 
of so large a quantity of oxygen, is converted into a blue oxyde which remains in so- 
lution. 
Tt 2 
