II. The Kffect oj Pressure upon Arc Spectra. 

 No. 3. Silver, X 4000 to X 4600. No. t.Gold. 



By W. GEOFFREY DUFFIELD, D.Sc., Honorary Research Felloiv in Physics 



in the University of Manchester. 



Communicated by ARTHUR SCHUSTER, F.R.S. 



No. 3. Silver, X 4000 to X4600. [PLATE l.] 



(Received January 9, Read February 4, 1909.) 



CONTENTS. 



1. Preliminary 



2. The apparatus 



3. The behaviour of the silver arc under high pressures 



4. The photographs 



(1) Method of exposure 



(2) Description of the plates 



5. The broadening of the lines 



6. The structural character of the wings of some broadened lines . . 



7. The displacement of the lines 



(1) Method of measurement 



(2) Table of the displacements 



(3) The relation between the pressure and the displacement . 



8. Changes in relative intensity under pressure 



9. Series of lines in the silver spectrum 



10. The banded spectrum produced under pressure 



(1) The structure of the banded spectrum . 



(2) The broadening of the bands 



(3) Table of wave-lengths and intensities of bands . 



(4) Relative intensities under pressure 



11. The continuous spectrum 



12. Influence of the electrical conditions upon the nature of the spectrum 

 Origin of the banded and continuous spectra. . . 

 Summary of results. (See ' Roy. Soc. Proc.,' A, vol. 84, p. 118, 1910.) 



VOL. CCXI. A 472. 



20.3.11 



