OF ARKANSAS. 85 



this saltpetre earth, which shows it to he rich in nitre salts, associated 

 with abundance of sulphate of lime. 



From a hopper of this earth, containing about 200 bushels, 1000 pounds 

 of salt-petre have been obtained, after being treated with lye, and crystal- 

 lized by evaporation in kettles, in a very rude manner. This would be 

 equal to about 5 pounds to the bushel. But it is estimated, that there must 

 have been a loss of at least one-third from leakage, overflow of the receiv- 

 ing trough during rainy weather, and other causes. 



When the quantitative analysis of this earth shall have been completed, 

 we shall be able to give a more precise estimate of the per centage of 

 nitre-salts which it actually contains. 



It appears that this cave must have been once the habitation of the 

 aboriginees, since not only bones of men, animals, and birds, such as the 

 buffalo, deer, and turkey, have been found, on removing the earth ; but even 

 the entire skeleton of an infant, enveloped in rags, and lying in a willow- 

 basket. The bones are frequently found under a bed of ashes. A polished 

 ivory breast dirk, with three holes in it, for the attachment of a handle, 

 and a long piece of rope, were also found in this cave, together with a 

 broken sea shell (Pyrula). 



There is reason to believe, too, from these and other relics and appear- 

 ances in the cave, that it has been worked, to a limited extent, for nitre, 

 in the early settlement of the country. 



The accumulation of organic matter, mixed with the earth of this cave, 

 is so profuse that it emits a strong ammoniacal odor, wherever it has 

 been stirred up and recently exposed by excavations. I infer, from the 

 presence of animal exuviae— one of the chief requisites for the formation 

 of nitre-salts — as well as from the approximate results obtained by the 

 rude method hitherto employed in the manufacture of saltpetre on Cave 

 creek, that the earth of the Thompson saltpetre cave contains a larger 

 per centage of nitre-salts than any of the nitre-earths hitherto reported 

 on ; at least, that part accumulated within 150 feet of the mouth of the 

 cave. 



Beyond this, where the cave becomes low and contracted in its dimen- 

 sions, for a limited distance, the earth will, probably, not be found as 

 strongly impregnated with organic matter, and, therefore, proportionally 

 less productive in saltpetre. 



This cave has several branches, which have been followed for some 

 hundred yards ; these may also contain some nitre-earth ; but as the floor 

 is covered with large blocks of tumbled rock, the underlying earths are 

 not accessible without considerable labor. 



