DOMAIN XII. VOLCANIC. 



and of some other parts of Auvergne, where fine 

 lentils of chalcedony, and chaicedonic crystal- 

 lised quartz, are found. The perlstein of Sancta 

 Fioray on the confines of Tuscany, is an analo- 

 gous chaicedonic substance, which is also found 

 in a tufo ; and the muller-glass, which was dis- 

 covered by Dr. Muller of Frankfort, and thought 

 to be a glass, is only a very fine chaicedonic 

 substance, with the lustre and transparence of 

 glass. Muller observed this substance formed 

 in drops on a porous lava*. I have found it on 

 the tufos of Bocheneim, near Frankfort, spread 

 like a shining varnish, and pretty thick, on the 

 surface. 



" Of some substances of the organised kingdom, 

 which are accidentally found in tufos. 



Bt iu e t s ufo imd " L The fossil tusks of the ele P hant have 

 been found in tufo in the neighbourhood of 



Rome. The Duke of Rochefoucault found one 

 himself of a gigantic size, as it was eight feet 

 long and fourteen inches in circumference : he 



* Faujas has added, Geol. ii. 147, that Muller said t him., 

 " I have infinite obligations to natural history, it charms my last 

 moments, and the weight of ninety-Jive years, my present age, does 

 not weaken its power. One has always fresh enjoyments 3 one lives 

 without reproach, and one does not die, but falls asleep" 



