LIST OF ILLUSTRATIONS. 



Plates 1 to 5. Dr. W. GEOFFREY DUFFIELD on the Effect of Pressure upon Arc 

 Spectra. No. 5. Nickel, X 3450 to X 5500. 



Plate G. Prof. C. FREWEN JENKIN and Mr. D. R PYE on Thermal Properties of 

 Carbonic Acid at Low Temperatures. (Second Paper.) 



