236 



REPORTS ON INVESTIGATIONS AND PROJECTS. 



(9) Increases the stability of the cellular structure. 



(10) The rate of grain-growth of the ferrite is inversely as the carbon- 

 content of the steel. 



Of these laws Nos. (i) and (3), even if hitherto unenunciated, have 

 probably been in the minds of many investigators. The others I believe to 

 be new. Nos. (4) and (10) need further confirmation. I do not give here 

 the pre-existing laws which I have either proved or confirmed. 



From law (5) and from other facts enumerated it is clear that the sta- 

 bility of the cellular structure and of the Widmanstattian figuring, which is 

 identical with that of meteoric iron, and other structural features, are pro- 

 foundly influenced by ante-natal conditions ; i. e., by the conditions to which 

 the austenite is exposed before these structures come into existence. The 

 relations between these scattered surprising effects are pointed out and an 

 explanation of them is offered. 



Nichols, E. L., Cornell University, Ithaca, New York. Grant No. 699. 

 Contimiation of researches of phosphorescence and fluorescence. (For 

 previous reports see Year Books Nos, 4-9.) $3,000 



The investigations during the past year have been largely devoted to the 

 study of the fluorescence and of the absorption spectra of various uranyl 

 salts. 



The fluorescence of these salts has in every case a spectrum consisting of a 

 group of narrow bands forming a spectral series of the type in which the 

 differences of frequency are constant or approximately so. The absorption 

 spectra likewise consist in every case of a group of bands similarly spaced 

 but of shorter wave-length. The differences of frequency in the group of 

 absorption bands are always less than in the fluorescence spectrum. The two 

 groups overlap to such an extent that where seven bands of the fluorescence 

 group are visible, three of these correspond to the three absorption bands of 

 greatest wave-length. 



In this overlapping region fluorescence and absorption are coincident as to 

 wave-length, or very nearly so, and this coincidence of two overlapping 

 series not having the same frequency difference is brought about by an 

 abrupt change in both series. For example, we find in one instance the fol- 

 lowing differences : 



Uranyl-potassium sulphate; wave-lengths and differences of frequency. 



Fluorescence. 

 4,350 4.472 4.614 

 Ai) 188 206 : 



4,765 

 4,760 



4,920 

 4,920 



5.130 

 5.127 



249 



251 



5.360 5.606 5,1 

 Absorption. 

 245 250 



6,190 



This extraordinary phenomenon is to be the subject of more detailed 

 investigations during the coming year. 



