CONTENTS. Vll 



PART SECOND. 



Page 

 XV. Some Experiments on the Milk of the Cow-Tree. By 



THOMAS THOMSON, M. D., F. R. SS. Lond. & Edin., 

 Professor of Chemistry in the University of Glasgow, - 235 

 XVI. Account of the Constituents of various Minerals. By 

 THOMAS THOMSON, M. D., F. R. SS. Lond. & Edin., 

 Professor of Chemistry in the University of Glasgow, - 244 



XVII. Account of a remarkable peculiarity in the Structure of 



Glauberite, which has one Axis of Double Refraction 

 for Violet, and two Axes for Red Light. By DAVID 

 BREWSTER, LL.D., F. R. SS. Lond. & Edin. - - 273 



XVIII. Experimental Inquiries concerning the Laws of Magne- 



tic Forces. By WILLIAM SNOW HARRIS, Esq. - 277 



XIX. On certain new Phenomena of Colour in Labrador Fel- 

 spar, with Observations on the nature and cause of its 

 Changeable Tints. By DAVID BREWSTER, LL.D., 

 F. R. SS. Lond. & Edin. - * - - -^ - 322 

 XX. On the Composition of Blende. By THOMAS THOMSON, 

 M. D., F. R. SS. Lond. & Edin., Professor of Chemistry, 

 Glasgow, . _ 332 



XXI. Notice regarding a Time-Keeper in the Hall of the Royal 



Society of Edinburgh. By JOHN ROBISON, Esq. Sec. 



R. S.Ed. . . .345 



XXII. On Asbestus, Chlorite, and Talc. By THOMAS THOM- 



SON, M. D., F. R. SS. Lond. & Edin. &c., Regius Profes- 

 sor of Chemistry in the University of Glasgow, - - 352 

 XXIII. Observations to determine the Dentition of the Dugong ; 

 to which are added Observations illustrating the Ana- 

 tomical Structure and Natural History of certain of 



