PRESSURE EFFECT UPON ABSORPTION. 573 



change in absorption due to increase in pressure and the relation of 

 this effect to the effects produced by lowering of temperature and 

 decrease in concentration, confront the experimenter as difficult 

 problems to be solved eventually by the theoretical physicist, 



The work described in this paper was done during a part of the year 

 in which the writer held the Sarah Berliner Research Fellowship. 

 In conclusion, she wishes to acknowledge her indebtedness to Professor 

 Lyman, Director of the Jefferson Physical Laboratory, for generously 

 extending to her the privileges of a guest in the laboratory, and to 

 Professor Saunders for suggestions with regard to the optical part of 

 the work, particularly in connection with the dyeing of plates used 

 in the deep red. She wishes especially to express her sincere thanks 

 to Professor Bridgman for his constant interest and valuable sugges- 

 tions and help during the whole course of the work. 



Vassar College, 



Poughkeepsie, N. Y. 



