164 FRAGMENTS OF SCIENCE. 



half the carbonic acid is appropriated by lime, the half 

 thus taken up, as well as the remaining half, being 

 precipitated. The solid precipitate is permitted to sink, 

 and the clear supernatant liquid is limpid soft water. 



"We returned to the real mouth of St. Michael's 

 Cave, which is entered by a wicket. The floor was 

 somewhat muddy, and the roof and walls were wet. We 

 soon found ourselves in the midst of a natural temple, 

 where tall columns sprang complete from floor to roof, 

 while incipient columns were growing to meet each 

 other, upwards and downwards. The water which 

 trickles from the stalactite, after having in part yielded 

 up its carbonate of lime, falls upon the floor vertically 

 underneath, and there builds the stalagmite. Conse- 

 quently, the pillars grow from above and below simul- 

 taneously, along the same vertical. It is easy to dis- 

 tinguish the stalagmitic from the stalactitic portion of 

 the pillars. The former is always divided into short 

 segments by protuberant rings, as if deposited period- 

 ically, while the latter presents a uniform surface. In 

 some cases the points of inverted cones of stalactite 

 rested on the centres of pillars of stalagmite. The 

 process of solidification and the consequent architecture 

 were alike beautiful. 



We followed our guide through various branches 

 and arms of the cave, climbed and descended steps, 

 halted at the edges of dark shafts and apertures, and 

 squeezed ourselves through narrow passages. From time 

 to time we halted, while Mr. Crookes illuminated with 

 ignited magnesium wire, the roof, columns, dependent 

 spears, and graceful drapery of the stalactites. Once, 

 coming to a magnificent cluster of icicle-like spears, we 

 helped ourselves to specimens. There was some diffi- 

 culty in detaching the more delicate ones, their fragility 

 was so great. A consciousness of vandalism, which 



