IV CONTENTS OF VOL. XXXI. — THIRD SERIES. 



Page 

 Mr. W. R. Grove on certain Phsenomena of Voltaic Ignition and 

 the Decomposition of Water into its constituent Gases by- 

 Heat (concluded) 91 



Mr. \V. R. Grove's Supplementary Paper on certain Phaeno- 

 mena of Voltaic Ignition and the Decomposition of Water 



into its constituent Gases by Heat . . ' 96 



Sir D. Brewster on the Modification of the Doubly Refracting 

 and Physical Structure of Topaz, by Elastic Forces emanating 



from Minute Cavities. (With a Plate) 101 



Sir R. Kane's Researches on the Composition and Characters of 

 certain Soils and Waters belonging to the Flax districts of 

 Belgium, and on the Chemical Constitution of the Ashes of 



the Flax Plant (concluded) . . . . 105 



Mr. J. P. Joule on the Theoretical Velocity of Sound 114 



Mr. E. C. Nicholson on the Composition of CafFein, and of some 



of its Compounds 115 



Prof. J. R. Young's Note in reference to the extension of Euler's 



Theorem 123 



Prof. A. Connell on the Precipitate produced in Spring and 



River Waters by Acetate of Lead 124 



Mr. J. Mercer on the Action of a mixture of Red Prussiate of 



Potash and Caustic Alkali upon Colouring Matters 126 



Dr. W. Gregory on the Preparation of Hippuric Acid 127 



Proceedings of the Cambridge Philosophical Society 130 



Royal Astronomical Society 143 



On a new Test for Prussic Acid, and on a simple method of pre- 

 paring the Sulphocyanide of Ammonium, by Prof. Liebig . . 146 



On the Fusion of Iridium and Rhodium, by R. Hare 147 



On Testing the Comparative Value of Astringent Substances for 



the purposes of Tanning, by Robert Warington, Esq 150 



On the two varieties of Arsenious Acid, by M. Bussy 151 



On the Preparation of Gun-Cotton 152 



On Balsam of Tolu, and some products derived from it 153 



On the Equivalent of Titanium, by M. Isidore Pierre 155 



On a modification of the Apparatus of Varrentrapp and Will for 



the estimation of Nitrogen, by Warren De la Rue, Esq 156 



On the Detection of Cotton in Linen, by G. C. Kindt 157 



The Planet Hebe 158 



Meteorological Observations for June 1847 159 



Table 160 



NUMBER CCVIL— SEPTEMBER. 



Dr. T. Anderson on certain Products of Decomposition of the 

 Fixed Oils in contact with Sulphur 161 



Mr. J. P. Joule on the Mechanical Equivalent of Heat, as de- 

 termined by the Heat evolved by the Friction of Fluids. ... 173 



