ir CONTENTS OF VOL. XII. — FOURTH SERIES. 



I'age 

 Prof. Sylvester on Professor Galbraith's Construction for the 



Range of Projectiles 112 



Mr. H. M. Witt on the Variations in the Chemical Composition 



of the Thames Water, during the year between May 1855 



and May 1856 114 



Mr. J. Cockle on the Resolution of Algebraic Equations of the 



Fifth Degree 124 



Mr. H. J. Brooke on a substance named Bleiniere in modern 



Treatises on Mineralogy 126 



Mr. H. C. Sorby on the Theory of the Origin of Slaty Cleavage. 127 



Prof. Tyndall's Observations on the preceding Paper 129 



Sir W. Snow Harris on certain Phaenomena of Electrical Dis. 



charge ^» 136 



Proceedings of the Royal Society 141 



Geological Society 149 



On the Heat absorbed in Chemical Decompositions, by J. P. Joule. 155 



On the Cleavageof compressed White Lead, by Warren De la Rue. 157 

 On the Behaviour of Iodide of Silver towards Ammonia, by 



Dr. A. Vogel, Juu 157 



Electrolytical Investigations, by M. Magnus 157 



Meteorological Observations for June 1856 159 



; Table • 160 



NUMBER LXXVIII.— SEPTEMBER. 



Prof. Tyndall's further Researches on the Polarity of the Dia- 



magnetic Force 161 



Mr. C Marett's Attempt to investigate the Causes of the Inter- 

 vals between High-water and Slack-water, and between the 



turn of Tide near the Shore and in the Offing. , 1 84 



Dr. Atkinson's Chemical Notices from Foreign Journals 188 



Sir J. F. W. Herschel on Slaty Cleavage, and the Contortions 



of Rocks 197 



Dr. A. Matthiessen's Preliminary Notice on the Electric Con- 

 ducting Power of the Alkaline Metals 199 



Dr. Schunck on Rubian and its Products of Decomposition. — 



Part III 200 



Prof. Stevelly on the Doctrine of Parallel Lines considered in a 



new Method 220 



Prof. Airy on Scheutz's Calculating Machine 225 



Proceedings of the Royal Society 226 



Absorption of Heat by Decomposition, by Dr. Woods 233 



Observations and Experiments upon the employment of Iodide 



of Potassium as a Reagent for Ozone, by S. Cloez 237 



On the Presence of Mercury in the native Argentiferous Copper 



of Lake Superior, by M. Hautefeuille 238 



Meteorological Observations for July 1856 239 



Table ... 240 



