vl CONTENTS OF VOL. XXI,——FOURTH SERIES. 
Page 
On the presence of Arsenic and Antimony in the Sources and 4 
Beds of Streams and Rivers, by Dugald Campbell, Esq..... 318 
Note on a Modification of the Apparatus employed for one of 
Ampeéere’s fundamental Experiments in Electrodynamics, by 
Profensar Wait: ei ess s 0 2, lae ge PU glee ae oni! nity pile 319 
Note respecting Ozone, by G. Gore, Esq. .....02..2222 0008 320 
NUMBER CXLI.—MAY. 
M. L. Lorenz on the Determination of the Direction of the Vi- 
brations of Polarized Light by means of Diffraction ...... 321 
Mr. T. Tate on certain Laws relating to the Boiling-points of 
different Liquids at the ordinary Pressure of the Atmosphere. 331 
Prof. Maxwell on Physical Lines of Force ................ 3838 
Mr. G. B. Jerrard’s Remarks on Mr. Cayley’s Note’... eee 348 
Mr. J. Stuart Glennie on the Principles of piper S tox 
Part II. Molecular Mechanics . sal el Ge 
Dr. Atkinson’s Chemical Notices from Foreign Journals .... 358 
Prof. Rijke on the Duration of the Spark which accompanies ~ 
the Discharge of an Electrical Conductor................ 365 
Prof. Sylvester’s Note on the Historical Origin of the unsym- 
metrical Six-valued Function of six Letters.............. 369 
Dr, Ph. Carl on the Galvanic Polarization of buried Metal Plates. 377 
Mr. J. Cockle on Transcendental and Algebraic Solution .... 379 
Proceedings of the Royal Society :— 
Mr. J. A. Broun on the Lunar-diurnal Variation of Mag- 
netic Declination at the Magnetic Equator.......... 384 
Mr. B. Stewart on the Nature of the Light emitted by 
heated Faumbaline), 7 isa). dean's Levin aale s Gee 391 
On the Motion of the Strings of a Violin, by Prof. H. Helmholtz. 393 
On Clairaut’s Theorem, by Prof. Hennessy, F.R.S. ........ 396 
On a Method of taking Vapour-densities at Low Temperatures, 
by Dr. Lyon Playfair, and J. A. Wanklyn................ 398 
NUMBER CXLII.—JUNE. 
Mr. J. J. Waterston on a Law of Liquid Expansion that con- 
nects the Volume of a Liquid with its Temperature and with 
the Density of its saturated Vapour. (With a Plate.)...... 401 
Prof. Kobell on a peculiar Acid (Dianic Acid) met with in the 
Group of Tantalum and Niobium compounds............ 415 
Mr. A. Cayley on the Partitions of a Close................ 424 
Prof. Chapman on the Drift Deposits of Western Canada, and 
on the Ancient Extension of the Lake Area of that Region . 428 
Mr. F. Field on the Neutralization of Colour in the mixtures of 
Miolutions of certain Salts <.),.... s; -ne. ees » 5 eee 435 
M. H. Fizeau on several Phenomena connected with the Polari- 
vation of. Light: id: d¢;. viele 4 raees ver seb eee’ } ase 438 
