the Carinthian Molybdate of Lead. 287 
Mr. Klaproth says, that by previous experiments he had 
found, that nitric acid much diluted did not attack the ore 
when cold ; and therefore to separate it from the soluble ma- 
trix, he successively poured small quantities of the diluted acid 
on the ore till all effervescence had ceased, after which the ore 
was washed and dried. The nitric acid which had been em- 
ployed was found to contain calcareous earth, and also a con- 
siderable quantity of red oxyde of iron, which upon being dis- 
solved in sulphuric acid, left a residuum of lead and siliceous 
earth.* 
Two drachms of the purified ore were mixed with an equal 
quantity of pot-ash, and afterwards exposed to the fire in a 
crucible. The mixture melted without intumescence. When 
cold, the mass was of a reddish colour, and the surface was 
covered with small scales. Water was poured on it, and the 
solution was saturated with nitric acid. The following day, 
the bottom of the glass was found covered with projecting 
crystals, about a quarter of an inch in length : these crystals 
were formed of small glittering rhomboidal plates, heaped one 
on the other. Their flavour was rather metallic. They 
quickly melted with the blow-pipe, on charcoal, without any 
increase of bulk, and became small round drops, which were 
immediately absorbed by the charcoal. When melted by the 
blow-pipe in a silver spoon, they appeared as small grains, of 
a greyish colour, which became streaked in cooling, and de- 
posited a white powder during the operation. 
When the phosphate of ammoniac and soda was melted, and 
some of these crystals were added, they speedily dissolved, 
* Analyse Chimique du Plomb Spathique jaune de Carinihie. Annales de Chimie , 
1791, pag. 103. a 
MDCCXCVI. P p 
