[ 202 ] 



XXVIII. Mineralogical Notices. Communicated by W. H. 

 MILLER, Esq., Professor of Mineralogy in the University 

 of Cambridge. 



[Continued from p. 105.] 

 ANALYSIS OF MONAZITE. 

 [From Poggendorff's Annalen, vol. xlvii. p. 385.] 

 E hundred parts of Monazite, the Mengite of Mr. 

 Brooke, analysed by M. Carl Kersten, gave 



Oxide of cerium 26*00 



Oxide of lantanium 23*4-0 



Thorina 17'95 



Oxide of tin 2'10 



Protoxide of manganese 1*86 



Lime 1*68 



Phosphoric acid 28*50 



Traces of potash and titanic acid. 



ANALYSES OF OCTAHEDRAL COPPER PYRITES. BYM.PLATTNER. 

 [From Poggendorff's Annalen, vol. xlvii. p. 351.] 



From Condurrow From the Woitzki From the Mar- 



XXIX. On the Use ofHydriodic Salts as Photographic Agents. 



By Mr. ROBERT HUNT.* 

 To the Editors of the Philosophical Magazine and Journal. 



GENTLEMEN, 



HAVE been engaged more than twelve months in study- 

 ing the peculiarities of the salts of hydriodic acid, when 

 used for the production of those photographic pictures which 

 are formed by one operation, having their lights and shadows 

 correct as in nature ; and the results of my very numerous 



* Communicated by the Author, whose former papers on Photography 

 will be found in vol. xvi. p. 138, 267 : see also our report of the proceed- 

 ings of the Royal Society for the past session. 



