234 Gases, Acids, Salts, ^c. 



12. Calcareous tufa, at Otsquago, and along the canaf. 



13. Living amphibious animals, in secondary rocks near 

 Whitesborough, and in Lockport. 



14. Living moluscous animals, in diluvial deposits. 



1. Nitrogen Gas. 



This gas issues continually, in a state of purity or nearly 

 so, from the earth, on John Bradt's farm in Hoosick, just 

 within the limits of Rensselaer county, in the state of New- 

 York. Dr. L. C. Beck and myself first tested it on the 17th 

 of August, in 1821. The underlying rock appears to be the 

 sparry lime rock, from a consideration of the surrounding 

 rock ; but the detritus is here deep, and conceals the rock. 



The gas probably issues from every part of a low hill, 

 comprising four or five acres of ground. For where there is 

 water, it becomes manifest by bubbling through it. It issues 

 abundantly from the hill through three springs, from the 

 clean gravelly bottoms of each. But it does not combine 

 with the water in either of them. Probably the gas accom- 

 panies the water from a considerable depth ; for the water 

 of the springs is not increased by the greatest spring and fall 

 freshets. 



The detritus appears to be very deep ; and both the water 

 and the gas may proceed from the underlying sparry lime 

 rock. This conjecture is strengthened by another fact. New 

 Lebanon springs are situated directly upon the sparry lime 

 rock ; which rock is in full view, and contiguous with that of 

 Hoosick springs. The public houses are built upon it, and 

 the same gas issues from New Lebanon springs, but in small- 

 er quantities. These springs are about twenty-five miles 

 south of the Hoosick springs. 



The hypothesis of Longchamps* might perhaps furnish a 

 plausible theory for the production of nitrogen gas at Hoo- 

 sick and New Lebanon. He maintains that " the oxygen 

 and nitrogen of the air unite and form nitric acid when in 

 contact with calcareous substances which are sufficiently 

 porous, and under the influence of a due proportion of heat 

 and moisture. As the sparry lime rock is often found porous 

 and of a spongy texture, it may cause the supposed union of 

 oxygen and nitrogen of the air, which comes in contact with 

 it at a considerable depth under the detritus. Here the tem- 



* His theory is disputed by Gay Lussac, and adopted by T. Graham. 



