Mr. Vanuxem's Description of a Lamellar Pyroxene. 131 



4. Spirit Lamp. 

 On the east of north, attracted : moved eastward. 

 On the west of north, ditto : ditto. 



On the east of south, ditto : moved westward. 

 On the west of south, repelled : ditto. 



5. Aphlogistic Lamp. 

 On the east of north, attracted : moved eastward. 

 On the west of north, repelled : ditto. 



On the east of south, attracted : moved westward. 

 On the west of south, repelled : ditto. 



6. Heated Plate of Zinc. 



On the east of north, repelled : moved eastward. 

 On the west of north, attracted : ditto. 

 On the east of south, repelled : moved westward. 

 On the west of south, attracted : ditto. 



7. Heated Plate of Silver. 



On the east of north, attracted : moved eastward. 

 On the west of north, ditto s ditto. 



On the east of south, ditto : moved westward. 

 On the west of south, ditto : ditto. 



The zinc and silver plates, merely heated, prove that positive 

 and negative electricity may be excited apart from chemical 

 action, and that the increment of temperature, superinduced by 

 the chemical action of the acid on the Voltaic plates, may be 

 the source of the communication of electric power. 



On the theory of these phasnomena I at present forbear to 

 touch ; an extension of such experiments appears to me, how- 

 ever, fraught with the solution which involves the variation of 

 the compass. The thermo-electricity of the globe, as produced 

 by the march of the sun in the plane of the ecliptic toward 

 the tropics of Cancer or of Capricorn, may occasion the grand 

 outlines of variation. Local peculiarities will give rise to par- 

 ticular deviations from the general law. 



Your obliged and obedient servant, 

 Chesterfield, Feb. 7, 1824. J. Murray. 



XXIV. Description, Analysis, Sfc. of a Lamellar Pyroxene. 



By Lardner Vanuxem.* 

 T^HIS mineral was brought last year from West Point by 

 "■• Professor Keating and myself; the locality, hitherto un- 

 published, having been shown to us by Captain Douglass, 

 Mathematical Professor of.the Military Academy. 



* From the Journal of the Academy of Natural Sciences of Philadelphia, 

 vol. iii. p. fi8. 



R 2 The 



