THE MAMMOTH CAVE OF KENTUCKY. 59, 



form the nitrate of lime. The red earth containing the nitrate of 

 lime was liquidated in vats, the water being conveyed through 

 wooden pipes made by boring poplar trees ; the liquid on becoming 

 saturated, was drawn off, and the nitre was extracted in the 

 ordinary way. 



We now wander a little further, and are introduced to the 

 "Methodist Church," so named from the fact of a body of 

 Methodists, meeting there for worship, between fifty and sixty 

 years ago .3 it is a large cavern, the roof of which appears to be 

 supported by props, which in reality are huge stalactites, and 

 stalagmites, varying from 8ft. to loft. high, and 3ft. round, to 

 smaller ones of only a few inches. Many of these have united, 

 and hence the apparent props to the roof. These stalactites show, 

 to some extent, the length of time the Cave has been in forming. 

 They are produced in this way : the rain water containing 

 carbonic acid absorbs the limestone above the Cave, till it reaches 

 the roof, here it hangs in drops for a long time -, evaporation takes 

 place, and the carbonic acid is given off, which causes a pre- 

 cipitation of the dissolved lime. 



It is much the same process which gives rise to boiler deposits 5 

 the water evaporates into steam, carbonic acid is driven off, 

 the remaining liquid becomes more saturated, and at last a 

 deposit takes place. So in the Cave, while the drop of water hangs 

 to the roof a similar precipitation goes on, and a stalactite is begun: 

 in the course of time it lengthens, and the drops of water run out 

 to the extreme end before they begin to deposit, and thus the 

 stalactite is developed. But the whole of these drops of water 

 are not evaporated, a portion drops to the floor of the cave, 

 and the same process going on produces a stalagmite {i.e., a 

 stalactite rising up from the ground,) which being directly under 

 the stalactite, meet after a long period of time and form a column. 

 In the Cheddar Cave, stalactites and stalagmites are to be seen j 

 but they are very small and insignincant when compared to those 

 of the Mammoth Cave, but they are clearer, and when struck, 

 resound with a musical note : this effect cannot be produced on 



