IV CONTENTS OP VOL. XX. — FOURTH SERIES. 



Page 

 The Rev. W. S. Symonds on the Physical Relations of the 



Reptiliferous Sandstone near Elgin 85 



Baron Anca de Mangalaviti on the Discovery of two Bone- 

 caves in Northern Sicily 86 



Chemical Analysis of two Mineral Products formed by Subli- 

 mation in the Eruption of Vesuvius in 1858, by M. Cappa. . 87 

 On the Fluozirconates, and on the Formula of Zirconia, by 

 C. Marignac 87 



NUMBER CXXXI.— AUGUST. 



Professors Kirchhoff and Bunsen's Chemical Analysis by Spec- 

 trum-observations. (With a Plate.) 89 



Messrs. A. H. Church and E. Owen on the Bases produced by 

 the Destructive Distillation of Peat 110 



M. G. R. Dahlander on a New Species of Figures of Equili- 

 brium for Revolving Fluids, the particles of which attract 

 one another according to Newton's Theory 119 



M. G. R. Dahlander on a Theorem relating to the Attraction 

 of the Ellipse 125 



Mr. W. R. Grove on the Transmission of Electrolysis across 

 Glass 126 



Prof. Breithaupt's Preliminary Notice on Thirteen Systems of 

 Crystallization in the Mineral Kingdom, and their Optical 

 Characters 129 



Dr. Atkinson's Chemical Notices from Foreign Journals .... 139 



Mr. B. Stewart : Note regarding Mr. Ponton's Paper " On cer- 

 tain Laws of Chromatic Dispersion " 143 



Mr. J. Cockle's Sketch of a Theory of Transcendental Roots. 145 



Proceedings of the Royal Society : — 



Mr. G. Gore on the Movements of Liquid Metals and 

 Electrolytes in the Voltaic Circuit 149 



Proceedings of the Geological Society : — 



Mr. G. P. Wall on the Geology of part of Venezuela and of 

 Trinidad 164 



On the Formation of Ice at the bottom of Water, by M. Engel- 

 hardt 166 



On a remarkable Ice shower, by Captain Blakiston, R.A 168 



NUMBER CXXXII.- SEPTEMBER. 



Mr. B. Stewart on the Radiative Powers of Bodies with regard 

 to the Dark or Heat-producing Rays of the Spectrum 169 



Prof. Swan's Note on Professors Kirchhoff and Bunsen's Paper 

 " On Chemical Analysis by Spectrum-observations." 173 



M. C. Sainte-Claire Deville's Considerations in reference to M. 

 Rose's Memoir on the different conditions of Silicic Acid . . 175 



