' gieai and extraordinary Cave in Indiana. SI 
structure and appearance of the cave. It only remains to men- 
tion its productions. 
The first in importance is the Sulphate of Magnesia, or Ep- 
som salts, which, as has been previously remarked, abounds 
throughout this cave in almost its whole extent, and which I be- 
lieve has no parallel in the history of that article. This neutral 
salt is found in a great variety of forms, and in many different 
stages of formation. Sometimes in lumps, varying from one to 
ten pounds in weight. The earth exhibits a shining appear- 
ance, from the numerous particles interspersed throughout the 
huge piles of dirt collected in different parts of the cave. The 
walls are covered in different places with the same article, and 
reproduction goes on rapidly. With a view to ascertain this 
fact, I removed from a particular place every vestige of salt, 
and in four or five weeks the place was covered with small 
needle-shaped crystals, exhibiting the appearance of frost. 
The quality of the salt in this cave is inferior to none ; and 
when it takes its proper stand in regular and domestic practice, 
must be of national utility. With respect to the resources of this 
cave, I will venture to say, that every competent judge must pro- 
nounce it inexhaustible. The worst earth that has been tried, will 
yield four pounds of salt to the bushel ; and the best from 
'twenty to twenty-five pounds. 
The next production is the Nitrate of Lime, or saltpetre earth. 
There are vast quantities of this earth, and*equal in strength to 
any that I have ever seen. There are also large quantities of the 
Nitrate of Alumina, or nitrate of argil, which will yield as much 
nitrate of potash, or saltpetre, in proportion to the quantities of 
earth, as the nitrate of lime. 
The three articles above enumerated are first in quantity and 
importance ; but there are several others which deserve notice, 
as subjects of philosophical curiosity. The Sulphate of Lime, or 
plaster of Paris, is to be seen variously formed ; ponderous, 
crystallized and impalpable or soft, light, and rather spongy. 
Vestiges of the sulphate of iron are also to be seen in one or two 
places. Small specimens of the carbonate, and also the nitrate 
of magnesia, have been found. The rocks in the cave princi- 
pally consist of carbonate of lime, or common limestone. 
I had almost forgotten to state, that near the forks of the cave 
