Vm CONTENTS OF VOL. XVI. — FOURTH SERIES. 



Page 

 Observations on Mr. Couper's New Chemical Theory, by M. A. 



Kekule 478 



Meteoric Stone of Borkut 479 



On Crystallized Valerianate of Atropine, by H. Callmann 480 



Crystallized Furnace-products 480 



NUMBER ex.— SUPPLEMENT TO VOL. XVL 



Mr. J.J. Waterston on the Theory of Sound 481 



Prof. Secchi on Solar Spots, and the Method of determining 



their Depth 495 



Mr. D. '\''aughan on Luminous Meteors and I'emporary Stars. 500 



M. B. W. Feddersen on the Electric Spark 503 



Dr. Atkinson's Chemical Notices from Foreign Journals .... 516 

 Proceedings of the Royal Society: — 



Drs. Williamson and Russell on the Measurement of Gases 



in Analysis 524 



Mr. R. Moon on the Theory of Internal Resistance and 

 Internal Friction in Fluids; and on the Theories of 



Sound and of Auscultation 528 



Mr. T. Hopkins on the Influence of Heated Terrestrial 



Surfaces in disturbing the Atmospliere 531 



Dr. Hofmann on the Poly-ammonias 532 



Mr. W. Fairbairn on the Resistance of Tubes to collapse. 534 

 Baron Pollock on some Remarkable Relations which obtain 

 among the Roots of the Four Squares into which a 



Number may be divided 537 



Proceedings of the Geological Society : — 



Sir R. I. Murchison on the Geological Structure of the 

 North of Scotland and the Orkney and Shetland Islands. 543 

 On some Properties of Ice near its Melting-point, by Professor 



J. D. Forbes 544 



Index 547 



PLATE. 



I. Illustrative of Prof. Pliicker's Paper on the Action of the Magnet 

 upon the Electrical Discharge in Rarefied Gases, and M. Fed- 

 dersen's on the Electric Spark. 



