GEOLOGICAL SOCIETY OF PENNSYLVANIA. 



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dered as an old alluvion, deposited while the cave was a 

 subterraneous stream or river, or as a disintegration of the 

 rock which is daily in progression, we are not prepared 

 to say ; but however it may be, it can in no manner 

 elucidate the geological nature of the surrounding country. 



found no water worn pebbles nor any fragments of other rocks. The bones 

 which were found (and the earth which contained the bones was dug up to 

 the very floor), are very few compared with the large quantity of saltpetre 

 produced. I was told that sometimes more than 400 men at one time were 

 engaged in it, and of course the decomposition of the flesh of these few ani- 

 mals could not have produced the nitrogen necessary for the nitric acid ; there 

 are besides found large numbers of quills of porcupine, as I am told, but even 

 these are not so abundant, because I found not a single one. But is organic 

 matter absolutely necessary to produce nitrogen in such a state that it enters 

 in combination with oxygen? Nascent nitrogen, it is said, combines with 

 oxygen and forms the acid ; but why should not nitrogen, when in favourable 

 circumstances, enter into combination with oxygen, though not exactly at the 

 moment it was produced ? Here in our caves, every thing seems favourable 

 to this combination. 



Although the wind, when we entered the cave, blew in such a direction 

 that it ought to have entered through the Arched cave in Warren county, and 

 Consequently have blown out of the entrance by which we went in, neverthe- 

 less we did not meet any current of air ; on the contrary the air was rushing 

 in through the same aperture. We had at first some difliculty to keep 

 our lights burning ; but when we had advanced some distance, the draught di- 

 minished very much, and we soon folt no current of air at all, our lights burnt 

 quiet and bright, and, though apparently stagnant, the air was pure, delight- 

 ful and invigorating ; the workmen told me it was the most healthy occupation 

 they ever were engaged in. It had frozen early in the morning, and was still 

 very cold when we entered the cave ; of course we found the temperature of 

 the interior very agreeable. We remained several hours in it, the sun was 

 near the meridian and the atmosphere quite warm when we came out, but 

 still the air rushed into the cave and was very perceptible when we began to 

 approach the entrance, even before we could perceive daylight; so the rush- 

 ing in of air could not be attributed to a dilatation or condensation of it by the 

 diff'erence of temperature. The air was dry, but sufliciently moist to make 

 the earth feel damp, and was not dusty ; though the earth contained much 

 saltpetre, I no where saw efflorescences of that salt ; the earth was loose, light, 

 and, independently of the saltpetre, which is dispersed through it in very ir- 

 regular proportions, is composed of silex, carbonate of lime, and a small pro- 

 portion of alumine and magnesia. But the earth from the floor is not preferred 

 by the workmen ; they often take the lower part of the sides of the cave, even 

 peeling ofi" about an inch deep from the rock, which they say is more pro- 

 ductive. 



Inasmuch then, as the air in the cave was stagnant, or apparently so, and as 

 we found nevertheless that a constant current of air was flowing in, it follows 

 that an absorption or decomposition of the air must take place in the cave. 



