260 Account of some new Vesuvian Minerals. 
effervescence, and forms a globule of white enamel, with the ~ 
aspect of porcelain. With the nitrate of cobalt it acquires & 
most beautiful azure. With phosphorus, in proper propor- 
tions, it gives a milky button, which remains opaque ; but 
when the phosphorus is in excess, the button is transparent 
when warm, but opaque when cool. 
Varieties. 1. Primitive. 2. Annular. 3. Peri-dode- 
cahedral. 4. Emarginate. (fig. 198.) 5. The same short- 
ened. (fig. 199.) 6. Pyramidal. (fig. 200.) 7. The same 
shortened. (fig. 201.) 
= Dimensions. The crystals are usually lafger than those of 
r . ee + ; 
ce ie but those of the primitive and annular varieties are 
small, passing into microscopic. 
Cavolinite occurs, Ist. In the imterior of 
