Trans. N. Y. Ac. Set. 136 Mar. 13, 



cavities are chiefly water and carbon di-oxide, with a small proportion 

 of nitrogen. 



1 noticed some curious phenomena in a single fragment, which had 

 by some means escaped destruction by freezing. 



This specimen had several small cavities, arranged nearly parallel 

 to each other. At temperatures below 70° a small bubble could be 

 plainly seen to move in each cavity, as the position of the specimen was 

 changed. It was further noticed that the cavities contained two 

 liquids, in one of which the bubble was wholly confined in its move- 

 ments. This was seen to be the central and more transparent fluid. 



If this specimen was slightly heated (the mere heat of the hand was 

 found sufficient), the bubbles would grow gradually less until they 

 disappeared entirely, and the fluids would unite. 



On cooling, a critical temperature would be reached, when all the 

 cavities would be filled with numberless minute bubbles, which, rushing 

 together, would in a few seconds form to its full size the bubtjle oiigin- 

 ally noticed. I found that this experiment could be repeated indefinitely, 

 without any diminution of its interesting phenomena or risk of damage 

 to the specimen. 



To Alexander county, North Carolina, and to many of the surround- 

 ing counties, we can hereafter look to produce fluid-bearing quartz 

 crystals second in interest to those of no other region in the world. 



[Mr. Hidden's communication was illustrated with a very striking 

 series of inclusion crystals, and of the fragments split off by the frost 

 from the large crystals, as dcsciibed. The pieces were in the form of 

 large flakes or plates, parallel to the faces of the rhombohedron, and 

 were clouded and filled with elongated or rod-shaped cavities, in im- 

 mense numbers and of conspicuous size.] 



March 13, 1882. 



Section of ChExMistry. 



The President, Dr. J. S. Newberry, in the Chair, 

 Thirty persons present. 



Prof. D. S. Martin, in behalf of Mr. Kunz, exhibited a series 

 of crystals of Diopside, from the town of DeKalb, St. Lawrence Co., 

 N. Y. This variety of pyroxene has never before been discovered, it 

 is believed, in this country, though long known from the two locali- 

 ties of Ala and Traversella, in Piedmont. Its occurrence here is 

 therefore, a matter of much interest ; and the beauty and transpa- 



