'9"4.] MINUTES. 



IX 



" Behavior of Metals and Other Substances Under Stress Near 

 the Rupture Point," by A. A. Michelson, Ph.D., LL.D., Pro- 

 fessor of Physics, University of Chicago. Discussed by Prof. 

 E. W. Brown, Mr. Bridgman, and Mr. Brush. 



" On Highly Radio-Active Solutions," by William Duane, A.M., 

 Ph.D., Assistant Professor of Physics and Research Fellow 

 of the Cancer Commission, Harvard University. (Introduced 

 by Prof. Goodspeed.) Discussed by ]\Ir. Brush and Dr. 

 Donaldson. 



" Some Further Considerations in the Development of the Elec- 

 tron Conception of Valence," by K. G. Falk, of the Harriman 

 Research Laboratory, Roosevelt Hospital, New York. (In- 

 troduced by Prof. Bogert). 



"The Valence of Nitrogen in Ammonium Salts," by William 

 Albert Noyes, Ph.D., LL.D., Professor of Chemistry, Uni- 

 versity of Illinois, and R. S. Potter. (Introduced by Prof. 

 H. C. Jones.) 



" Determination of the True Atomic ^^'eight of Radium," by 

 Gustavus Hinrichs, of St. Louis. 



Afternoon Session — 2 o'clock. 



Edward S. Pickering, D.Sc, LL.D., F.R.S., 



Vice-President, in the Chair. 



Dr. Cyrus Adler in presenting a portrait of the late Samuel Pier- 

 pont Langley, LL.D., a former Vice-President of the Society, spoke 

 as follows : 



On behalf of a number of members of the Society I have the 

 honor to present a portrait of Samuel Pierpont Langley, a former 

 member and A'ice President of the American Philosophical Society. 



Mr. Langley, the third Secretary of the Smithsonian Institution, 

 was a man of national and international fame which rested primarily 

 upon his epoch making researches in solar physics. All of the 

 recognition which came to him was based upon his discoveries in 

 physics and astronomy. But he was also a pioneer in another field, 

 being the first distinguished man of science to devote himself to the 



