HENRI and JEAN BECQUEREL and H. KAMERLINGH ONNES: “On phos- 
phorescence at very low temperatures.” PI. n. 
Fig. 7. 
% % It 
Fig. 9. 
Fig. 10. 
80° K. 
Fig. 13. 
80° K 
Proceedings Royal Acad. Amsterdam. Vol. XII. 
