130 THE CRUISE OF THE BETSEY ; OR, 



lactites pass through. In the vesicle in which this hollow 

 pebble was formed three consecutive processes must have 

 gone on. First, a process of infiltration coated the interior 

 all around with layer after layer, now of one mineral sub- 

 stance, now of another, as a plasterer coats over the sides and 

 ceiling of a room with successive layers of lime, putty, and 

 stucco ; and had this process gone on, the whole cell would 

 have been filled with a pale-zoned agate. But it ceased, and 

 a new process began. A chalcedonic infiltration gradually 

 entered from above ; and, instead of coating over the walls, 

 roof, and floor, it hardened into a group of spear-like stalac- 

 tites, that lengthened by slow degrees, till some of them had 

 traversed the entire cavity from top to bottom. And then 

 this second process ceased like the first, and a third com- 

 menced. An infiltration of lime took place ; and the minute 

 calcareous molecules, under the influence of the law of crys- 

 tallization, built themselves up on the floor into a large smooth- 

 sided rhomb, resembling a closed sarcophagus resting in the 

 middle of some Egyptian cemetery. And then, the limestone 

 crystal completed, there ensued no after change. As shown 

 by some other specimens, however, there was a yet farther , 

 process : a pure quartzose deposition took place, that coated 

 not a few of the calcareous rhombs with sprigs of rock-crys- 

 tal. I found in the Scuir More several cellular agates in 

 which similar processes had gone on, none of them quite so 

 fine, however, as the one figured by M'Culloch ; but there 

 seemed no lack of evidence regarding the strange and multi- 

 farious chemistry that had been carried on in the vesicular 

 cavities of this mountain, as in the retorts of some vast labo- 

 ratory. Here was a vesicle filled with green earth, there 

 a vesicle filled with calcareous spar, yonder a vesicle crust- 

 ed round on a thin chalcedonic shell with rock-crystal, in 

 one cavity an agate had been elaborated, in another a helio- 

 trope, in a third a milk-white chalcedony, in a fourth a jasper. 



