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 Pliilosophical Magazine and Journ^il 220 
Mr. Halliwell’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 CIIL— 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. HI. On Electro -dynamic Induction {continued^ 254 
Th. Scheerer on the Natural Products which originate from 
the action of the Atmosphere on Iron Pyrites 265 
