_Micaceous Oxide of Iron_--in the iron mine in Hawley. _Green Carbonate of Copper_--in greenstone, in Greenfield. This ore constitutes a vein on the bank of Connecticut river, passing into the hill on one side, and under the river on the other. It has never been wrought, nor, indeed, is its locality publicly known. _Copper Pyrites_--in the same vein, not abundant, at the surface. _Sulphate of Barytes_--in the same place, constituting the immediate walls of the vein. Its breadth on the wall varies from an inch to a foot, and the breadth of the vein is 6 or 8 feet. _Galena_--in Whately. This is probably from a continuation of the vein of this ore that appears at Montgomery, Southampton, and Hatfield. A single crystal has been found in the same range, in Greenfield, twelve miles north of Whately; but it was not in place. _Red Oxyde of Titanium_--in Leyden, crystallized on quartz and tremolite, chiefly on the latter; colour brownish red--specific gravity 4.232; scratches glass, handsomely geniculated, and sometimes several geniculations in the same specimen; in one as many as six could be perceived. _Eagle Stone_, or _Nodular argillaceous Oxide of Iron_--one specimen on the banks of Deerfield river. _Rose-red Quartz_--a loose mass in alluvial soil, Deerfield. _Red Oxide of Titanium_--in Shelburne. I would acknowledge my peculiar obligations to Professor Silliman, of New-Haven, and to Dr. David Hunt, of Northampton, Mass. for the very generous assistance they have given me in a commencement of the study of mineralogy, and for their liberal aid in this particular communication. Their kindness, it is believed, will not soon be forgotten. To several others, also, I am indebted for communicating facts of importance. _Deerfield, October, 1817._ ART. II. _On the Prairies and Barrens of the West, by_ CALEB ATWATER, ESQ. _in Letters to the Editor_. CIRCLEVILLE, Ohio, May 28, 1818. _Dear Sir_, I send you for publication in the Journal of Science, an Essay on the Prairies and Barrens found in this country. _Description of the Prairies._