COLLECTION OF MINERALS. 299 



slabs, and extract from it the ultramarine blue 

 colour, which produces such a beautiful effect 

 upon stuffs, and is so unchangeable. Several of 

 the minerals, which follow, are not yet brought 

 into use, and are not worthy of much attention. 

 Amongst them, however, are some specimens of 

 a large size, such as the red stilbite and whitish 

 ajialcime, given to the Museum by M. Lucas, jun 1 . 



Mica, of which we see some large slabs in the 

 bottom of the thirtieth case, has been called 

 Muscovy glass, because it is employed in Russia 

 instead of window-glass. By the side of the 

 mica is asbestos, the filamentous variety of which 

 was known to the ancients under the name of 

 amiajithe, or incombustible flax, which they spun, 

 and made cloth and napkins of it. They threw 

 them into the fire when dirty ; by which means 

 they were made whiter than if they had been 

 steeped in lye. They \vrapt the bodies of their 

 dead in this stuff, when they wished to preserve 

 their ashes. We see, on one of the shelves, a speci- 

 men of this sort of cloth, which was made in Italy. 



The talc, which immediately follows, presents 

 also several varieties, which are interesting for 

 their uses ; such as the lapis ollaris, or potstone, 

 out of which vases are made on the turn-lathe ; 

 the Verona earth or green earth, which is em- 

 ployed \vith oil for painting landscapes ; and the 



