CONTENTS OF VOLUME XLII. 



NUMBER I. 



Page. 



Art. I. Notes of a Botanical Excursion to the Mountains of 

 North Carolina, &;c. ; with some remarks on the Bot- 

 any of the higher Alleghany Mountains ; by Asa Gkay, 



M. D., 1 



n. Account of three undescribed Plants of Central Ohio ; 



by Wm. S. Sullivant, - - - - 49 



in. Notes upon the Geology of the Western States ; by James 



Hall, - - - - - - 51 



IV. On the Perchlorate of the Oxide of Ethule, or Perchloric 



Ether ; by Clark Hare and Martin H. Boye, - 63 



V. A new Demonstration of the Principle of Virtual Veloci- 



ties ; by Prof. Theodore Strong, - - - 66 



VI. Solution of a Functional Equation, which has been em- 

 ployed by PoissoN in demonstrating the parallelogram 

 of forces ; by George R. Perkins, A. M., - - 69 



VII. Experiments on Bichlorure of Sulphur and certain car- 



bures of hydrogen ; by Prof. F. Chevet, - - 71 



VIII. Continuation of the Remarks made upon Arsenic, con- 

 sidered in a medico-legal point of view ; by J. Law- 

 rence Smith, M. D., - - - - - 75 

 IX. Remarks upon an examination of the Peroxide of Man- 

 ganese ; by Henry C. Lea, - - - - 81 

 X. A Sketch of the Infusoria of the family Bacillaria, with 

 some account of the most int(5resting species which 

 have been found in a recent or fossil state in the United 

 States ; with two plates, by Prof. J. W. Bailey, - 88 

 XI. Description of Eight new Species of Shells, native to 



the United States ; with a plate, by Henry C. Lea, - 106 



XII. Observations on the Storm of December 15, 1839 ; by 



William C. Redfield, A. M., - - - 112 



XIII. Temperature of the cities of Rome, (Italy,) and New 



York; by Jeremiah Van Rensselaer, M. D., - 120 



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