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of the city. This cavern has its mouth In 

 a rock of decompofed lava, and a man may 

 walk Into it to the diftance of fifty paces. 

 Its fides are covered with efflorefcences of 

 muriate of ammoniac, as were, likewife, 

 thofe of another fmaller cavern In the fame 

 rock. This fait muft have been formed by 

 fublimation, having been reduced to va- 

 pour by fubterraneous fires, and thus at- 

 tached itfelf to the fides of thefe two ca- 

 verns, as it is found attached in many other 

 volcanic places ; but of thefe fires and am- 

 moniacal vapours no traces whatever now 

 exift. 



In this fliort excurfion I found by the 

 way a volcanic breccia, which, on account 

 of the heterogeneous fubftances it contained, 

 it would be improper to pafs without notice. 

 It is found in large ifolated pieces, but I 

 was unable to difcover from what vein it 

 derived its origin. Its principal fubftance 

 is an earthy lava, of a blueifli grey, a coarfe 

 grain, and little hardnefs. In this were in- 

 clofed the following bodies : 



Firrt, 



