146 MINUTES OR MEETINGS. ^A^ 



This mineral, when exposed to the action of air and moist- 

 ure, is decomposed, forming the sulphured of iron, (green 

 vitriol,) which is soluble in water, producing thereby a 

 destruction of the stone. In consequence of the property 

 of the stone to absorb water, freezing also causes its disin- 

 tegration. When stone containing iron pyrites is laid in a 

 wall with lime mortar, it soon becomes stained with the 

 per-oxide of iron. The cause of this, probably, is that the 

 sulphur of the sulphuret of iron is converted into sulphuric 

 acid ; this, united with the lime of the mortar, forming the 

 sulphate of lime, the iron is converted into the peroxide, 

 thus causing the stain upon the surface of the stone. Those 

 quarries, belonging to this formation, that contain no sul- 

 phuret of iron, of which the Custom House at Sandusky, 

 and the United States Court House and Post Office in this 

 city are being built, are beautiful in appearance and dura- 

 ble in quality. 



Cleveland, January 22, 1858. 



The Academy met at the Medical College, Prof. Jared P. 

 Kirtland, President, in the chair. The minutes of the 

 previous meeting were read and approved. 



The President presented an Indian pipe, dug up on the 

 farm of Dr. Tousey, Pleasant Gap, Bates county, Missouri. 



Dr. Garlick presented a columella of the Pyrula per- 

 versa^ found about seven feet beneath the surface, near 

 Port Clinton, Ottawa county, Ohio. It had evidently been 

 used as an ornament by the aborigines. 



Col. Whittlesey read a paper on the Age of Trees, indi- 

 cated by their layers or rings. 



In the discussion which followed the reading of Col. 

 Whittlesey's paper. Prof. Cassels remarked that there 



