CONTENTS. V 



Page 



Phenomena of Calefaction 230 



Hydromellonic Acid 23 1 



Chromic Acid 231 



Composition of crystallized Phosphoric Acid 232 



Detection of Alcohol in Essential Oils 232 



(Economical Preparation of Acetone 233 



Carburet of Platina 234 



Sulphate of Carbyle 235 



On Hellenin, by Mons. C. Gerhardt 236 



Chemical and Contact Theories of Voltaic Electricity 237 



Hydromellonic Acid and Metallic Oxides 238 



Cyanilic Acid 239 



Meteorological Observations for July, 1840 239 



Table . 240 



NUMBER CX. OCTOBER. 



M. Jacobi's Comparative Measure of the Action of two Voltaic 



Pairs, the one Copper-zinc, the other Platina- zinc 241 



Mr. R. Potter on the Application of Huyghens's Principle in 



Physical Optics 243 



Mr. E. A. Parnell on Sulphocyanogen 249 



Mr. R. Hunt on the Use of Hydriodic Salts as Photographic 



Agents (concluded) 260 



Prof. Miller on the Form of Rutile . 268 



Mr. C.W.Hamilton's Note upon Mr. Griffith's Paper " upon 

 the true Order of Succession of the Older Stratified Rocks 



near Killarney and Dublin" 270 



Mr. Lubbock on the Heat of Vapours and on Astronomical 



Refractions (continued from vol. xvi. p. 569) 272 



Dr. Faraday on Magneto-electric Induction ; in a Letter to 



M. Gay-Lussac 281 



Mr. J. D. Smith on the Detection and Estimation of Colophony 



(common Rosin) when dissolved in the Fixed Oils 289 



Proceedings of the Royal Society 292 



. of the Geological Society 303 



of the Royal Astronomical Society 309 



Detection of lodate of Potash in Iodide of Potassium, by Mau- 

 rice Scanlan, Esq 316 



On Pepsin the Principle of Digestion 317 



Decrepitating Salt of Wieliczka, by H. Rose 318 



Meteorological Observations for August, 1840 319 



Table , . 320 



