LIST OF ILLUSTRATIONS. 



Plates 1-4. Dr. W. GEOFFREY DUFFIELD, on the Effect of Pressure upon Arc 

 Spectra. No. 3. Silver, X 4000 to X 4600. No. 4. Gold. 



Plates 5-7. Dr. WALTER ROSENHAIN and Mr. SYDNEY L. ARCHBUTT, A.I.C., on 

 the Constitution of the Alloys of Aluminium and Zinc. 



