CONTENTS. V 



Page 



Mr. Brooke on Haydenite and Couzeranite 175 



Rev. J. H. Pratt's Observations on the relative Temperature of 

 > the Sea and Air, and on other Phsenomena, made during a 



' Voyage from England to India 176 



Mr. J. Tovey's Researches in the Undulatory Theory of Light, 



continued : On the Absorption of Light 181 



Mr. G. J. Knox on the Direction and Mode of Propagation of 



the Electric Force traversing Interposed Media 185 



Researches on Fluorine 192 



On a simple mode of obtaining from a common Argand Oil 

 Lamp a greatly increased quantity of Light ; in a letter from 



Sir J. Herschel, Bart 194 



Mr. Gulliver's Observations on the Blood Corpuscles, or Red 



Particles of the Mammiferous Animals. No. Ill 195 



Prof. J. Henry's Contributions to Electricity and Magnetism. 



No. III. On Electro-dynamic Induction 200 



Researches of Mons. R. Piria on the Combinations of Salicyle 210 

 Mr. R. Potter's Letter to Richard Taylor, Esq., as Editor of 



the Philosophical Magazine and Journal 220 



Mr. HaUiwell's Additional Note on the Authenticity of the 

 disputed Passage in the treatise of Boetius de Geometria on 



Numerical Contractions . 221 



Dr. R. Kane on a Pseudomorphous variety of Iodide of Potas- 

 sium 222 



Proceedings of the Royal Irish Academy 224 



Precipitation of Iron by Zinc 235 



Action of Chlorine on the Carburetted Hydrogen of Acetates. . 235 



Hydrocarburet of Bromine 236 



Native Sulphate of Magnesia 236 



Manufacture of Chlorate of Potash 237 



Diabetic Blood and Urine 238 



•■ Sir John F. W. Herschel's new Researches on the Solar Spec- 

 trum and in Photography 239 



Meteorological Observations for January, 1840 239 



Table 240 



NUMBER cm.— APRIL. 



Letter from M. Kreil, Director of the Observatory at Milan, to 

 M. KupfFer, Director General of the Physical Observatories 

 in Russia, containing a succinct Account of the principal 

 Results of M. Kreil's Magnetic Observations at Milan 241 



Mr. J. D. Smith's Observations on the supposed Formation of 

 Inorganic Elements during Fermentation , 251 



Prof. J. Henry's Contributions to Electricity and Magnetism. 

 No. III. On Electro-dynamic Induction (continued) 254 



Th. Scheerer on the Natural Products w^hich originate from 

 the action of the Atmosphere on Iron Pyrites 265 



