11 CONTENTS. 



Page 

 Clikton, LL. D. President of the Lit. and Phil. Society of New 

 York, - - - - - - - 290 



XVII. On the Pyrophosphate of Soda, one of a new class of Salts produced by 

 the Action of ^eat on the Phosphates. By Mr Thomas Clark, Lec- 

 turer on Chemistry and Mechanics in tlie Glasgow Mechanics' Institu- 

 tion. Communicated by the Author, - - 298 



XVIII. On the Arseniate of Soda. By Mr Thomas Clark, Lecturer on 

 Chemistry and Mechanics in the Glasgow Mechanics' Institution. Com- 

 municated by the Author, . - , 309 



XIX. On a new Phosphate of Soda. By Mr Thomas Clark, Lecturer on 

 Chemistry and Mechanics in the Glasgow Mechanics' Institution. Com- 

 municated by the Author, - - - - 311 



XX. On the Crystalline Forms of Pyrophosphate of Soda and the Arseniate of 

 Soda, described in the preceding Papers. By William Haidinger, 

 Esq. F. R. S. E., &c. Communicated by the Author, - 314 



XXL On the Topography, Animals, and Reptiles of some districts in India. 



By P. Breton, Esq. - - - - 316 



XXII. On a peculiar Defect in the Eye, and a mode of correcting it. By 

 G. B. Airy, Esq. A. M., and Lucasian Professor of Mathematics in 



the University of Cambridge. With observations by the Editor, 322 



XXIII. On Davyne, a New Mineral Species. By William Haidinger, 

 Esq. F. R. S. E. &c. Communicated by the Author, - 320 



XXIV. Notice regarding the Structure aftd Mode of Generation of the Virgu- 

 laria mirabilis and Pennatula phosphorea. By Robert E. Grant, 

 M. D. F. R. S. E. F. L. S. Professor of Zoology in the University of 

 London. Communicated by the Author, - - 330 



XXV. Notice respecting Professor Barlow's New Achromatic Telescopes with 

 Fluid Object-Glasses, - _ - - - 335 



XXVI. On the Permanency of Achromatic Telescopes constructed with Fluid 

 Object-Glasses. By Archibald Blair, Esq. In a letter to Dr 

 Brewster, - - - - - 336 



XXVII. Mineralogical Notices, communicated by Dr Charles Hartman 

 of Blankenburg, of the Duke of Brunswick's Mining Service, M. W. S. 



&C. &c. Communicated by the Author, - - 342 



XXVIII. Notice respecting an Emigration of Butterflies. By P. Huber, 343 



XXIX. On the Permeability of Transparent Screens of extreme tenuity by 

 radiant Heat. By William Ritchie, A. M., Rector of Tain Aca- 

 demy, , . - - - 348 



XXX. On a new form of the Differential Thermometer, with some of its ap- 

 plications. By William Ritchie, A. M. Rector of Tain Academy, 360 



XXXI. Notice respecting Professor Hansteen's New Chart of the Isodynamic 

 Lines for the whole magnetic intensity. With a Chart, Plate IV. 

 Communicated by Professor Hansteen of Christiania, 351 



XXXII. On Berthierite, a New Mineral Species. By William Haidin- 



^ GER, Esq. F.R. S. E. &c. Communicated by the Author, 353 



XXXIIL ZOOLOGICAL COLLECTIONS, - - - 354 



1. On the Change in the Plumage of some Hen Pheasants. By W. , 

 Yarrell, Esq. F. L. S. - - - - ib. 



2. Observations on the Scarus of the Ancients. By Baron Cuvier, 355 



3. Notices regarding the Camelopard, - , - - 356 



4. On the Poison of the Rattlesnake, - - 357 



