the Carinthian Molybdate of Lead. 329 
porated ; and the following day I found a striated yellowish 
mass, which dissolved in water without leaving any residuum. 
This solution resembled the former in every respect. 
§ XIII. Molybdic Acid with Sulphur. 
In order to remove every doubt concerning the nature of 
the yellow acid obtained by the analysis, I made the follow- 
ing experiment. 
I put 20 grains of the yellow acid and 100 grains of sulphur 
into a small glass retort, and continued the distillation till the 
bottom began to melt. 
The residuum was a black substance, which was greasy to 
the touch, stained the fingers black, communicated to them 
a shining metallic lustre, and had all the other properties of 
the mineral known by the name of Molybdaena. 
I afterwards distilled this black matter with nitric acid, 
which converted it into a yellow powder, similar in appearance 
and properties to the molybdic acid which had been originally 
employed. 
§ XIV. General Observations. 
It has been proved in the course of this paper that molyb- 
date of lead can be decomposed in the humid way by the fixed 
alkalies, although these have not any effect when boiled with 
molybdaena mineralized by sulphur.* The state of the mo- 
lybdaena in the two substances appears to be the cause of this 
* Scheele’s Essays, p. 230 ; and Me'moire sur la Molybdene, par M. Pelletier. 
Journal de Physique, 1785, p. 437. 
Uu 2 
