OF ARTS AND SCIENCES, 261 



sistant Secretary of the Smithsonian Institution, offering to 

 transmit for the Academy, free of expense, to any part of 

 Europe, publications dehvered at Washington ; and also to 

 deliver, free of expense, at Washington, any publications in- 

 trusted to its agents in Europe. 



On motion of Mr. Tread well, it was 



" Voted, That the Corresponding Secretary be directed to present 

 the thanks of the Academy to the Smithsonian Institution for its oblig- 

 ing offer." 



Dr. C. T. Jackson communicated the results of his analysis 

 of a crystal of phosphate of lime from Hurdstown, New- 

 Jersey : — 



" This crystal has a pale lemon-yellow color, and possesses a re- 

 splendent lustre on the surface, resembling the glazing produced by 

 heat on a semi-fused mineral. Its specific gravity is 3.205. By 

 analysis it was found to consist of 



Phosphate of lime 92.405 



Chloride of calcium ...... 0.540 



Peroxide of iron ...... 0.040 



Oxide of manganese ...... 0.003 



Fluoride of calcium, by difference, . . . 7.012 



100.000 



" It is, therefore, identical with apatite, and nearly of the same com- 

 position as that from Capo de Gata in Spain. Its formula will be 

 3 Caa P + Ca (CI F). 



" This mineral occurs in large quantities at Hurdstown, and is 

 now extracted from the mine for use in agriculture ; it has been 

 also employed in England in the manufacture of earthen-ware. The 

 presence of fluorine in most, if not all, native phosphate of lime, 

 was remarked upon at a former meeting of the Academy, and its 

 agricultural importance was then indicated." 



Three hundred and forty-filth meeting. 



April 1, 1851. — Monthly Meeting. 

 The President in the chair. 

 Lieutenant Davis presented a paper, relating to the deterio- 



