TABLE OF CONTENTS 



TO THIS TWENTY-FIFTH VOLUME. 



JANUARY, J 8 10. 



Engravings of the following Subjects, in one Quarto Plate : Figures 1, 4, 5, d, 

 and 7, of Mr. Troughton's Apparatus for dividing Astronomical Instruments! 



I. An Account of a Metliod of dividing Astronomiqal and other Instruments, 

 by ocular Inspection ; in which the usual Tools for graduating are not em- 

 ployed; the whole Operation being so contrived, that no Errour can occur 

 but what is chargeable to Vision, when assisted by the best optical Means of 

 viewing and measuring minute Quantities. By Mr. Edward Troughton. 

 Communicated by the Astronomer Royal - . _ i 



II. On Platina and native Palladium from Brasil. By Wm. Hyde Wollaston 

 M.D. Sec. R. S. - - - - - 18 



III. On the Identity of Columbium and Tantaluin. By Wm. Hyde Wollaston 

 M. D. Sec. R. S. - - - . , 23 



IV. Inquiries concerning the Influence that Light exerts on the Propagation of 

 Sound. By Modeste Paroletti " - - - 28 



V. On the Chemical Action of simple Galvanico-elcctric Chains formed of 

 Metallic Solutions, Water, or Acid, and a Metal; and ou the Disoxidation of 

 Metallic Oxides effected by these Means. By Mr. Bucliolz - 39 



VI. Extract of a Letter on Potassated Iron from Mr. Hassenfratz, Engineer in 

 Chief of Mines, and Professor of Mineralogy at the Practical School of 

 Mines, to Mr. Gillet-Laumont, Correspondent of the Institute, and Member 

 of the Council of Mines. - - - -51 



VII. Analysis of the Aerolite that fell at Stannern in Moravia, the 22d of May, 

 1808. By Mr. Vauquelin - - - - 54 



VIII. Extract of a Letter from Mr. Klaproth to Mr. Gehlen - 59 



IX. On the Purification of Nickel by Means of Sulphuretted Hidrogen. By 

 Mr. Robiquet, Apothecary - - - - 61 



X. On the Experiments of Mr. Chenevix and Mr. Descotils on Platina. Bv 

 Mr. C. L. Berthollet - - - - - 65 



XI. On a singular Crystallization of the Diamond. By Mr. Guyton-Morveau 



67 



XII. Remarks on the Pechblende, an Ore of Uranium. By Mr. Vauquelin 69 



XIII. Proust on Oxides of Copper - - - . 7'2 

 Scientific News - . - . . j^y^_ 

 Meteorological Table ... , - 80 



FEBRUARY, 



