CONTENTS of N° 244.— Fourth Series. 



XLII. Notes on the Chemical Geology of the Gold-fields of Cali- 

 fornia. By J. Arthur Phillips page 321 



XLIII. On Discontinuous Movements of Fluids. By Professor 

 Helmholtz 337 



XLIV. On Unitation ; a novel Arithmetical Operation. By W. 

 H.Walenn, F.C.S 346 



XLV. On Riccati's Equation. By A. Cayley, F.R.S 348 



XLVI. On the New Electromotive Force in the Voltaic Arc. By 

 E. Edlund 352 



XLVII. On Geological Time, and the probable Date of the Glacial 

 and the Upper Miocene Period. By James Croll, of the Geological 

 Survey of Scotland 362 



XLVIII. Note on the Solvibility of Equations by means of Radicals. 

 By Professor Cayley, F.R.S 386 



XL1X. Proceedings of Learned Societies : — 



Royal Society: — Dr. W. H. Broadbent's attempt to apply 

 Chemical Principles in explanation of the Action of Poisons ; 

 Mr. W. Huggins on the Spectrum of Comet II., 1868 . 388-394 



L. Intelligence and Miscellaneous Articles : — 



On Stellar Spectra, by Father Secchi 394 



On a Thermo-rheometer, by M. Jamin 396 



Investigations on obscure Calorific Spectra, by M. Desains. ... 398 



*** It is requested that all Communications for this Work may be addressed, 

 post-paid, to the Care of Messrs. Taylor and Francis, Printing Office. Red 

 I, ion Court, Fleet Street, London. 



