May 9, 1913] 



SCIENCE 



727 



;oodness, lives not for time but for 

 eternity. ' ' 



On the Character and Adventures of Muladora: 

 Maurice Bloomfield, Ph.D., LL.D. 

 On Friday evening at the Hall of the Historical 

 Society of Pennsylvania George Grant MacCurdy, 

 A.M., Ph.D., assistant professor of archeology, 

 Yale University, gave an illustrated lecture on 

 "The Antiquity of Man in the Light of Recent 

 Discoveries." 



On Saturday morning at 9:30 o'clock an execu- 

 tive session was held in the hall of the society at 

 which candidates for membership were balloted 

 for. As a result of the election, the following new 

 members were announced: Residents of the United 

 States — George Francis Atkinson, Ph.D., Ithaca, 

 N. T.; Charles Edwin Bennett, A.B., Litt.D., 

 Ithaca, N. Y.; John Henry Comstock, B.S., Ithaca, 

 N. Y. ; Reginald Aldworth Daly, Boston, Mass.; 

 Luther Pf ahler Eisenhart, Princeton, N. J. ; 

 George W. Goethals, Culebra, Canal Zone; William 

 C. Gorgas, M.D., Sc.D., LL.D., Ancon, Canal Zone; 

 Koss G. Harrison, A.B., Ph.D., M.D., New Haven, 

 Conn.; George Aug^Jstus Hulett, Princeton, N. J.; 

 Clarence E. McClung, A.M., Ph.D., Swarthmore, 

 Pa.; John Dyneley Prince, Ph.D., Sterlington, 

 N. Y. ; Samuel Eea, Sc.D., Bryn Mawr, Pa. ; Henry 

 Norris Russell, Ph.D., Princeton, N. J.; Charles 

 Schuehert, New Haven, Conn.; Witmer Stone, 

 A.M., Philadelphia. Foreign Residents — Sir Ar- 

 thur John Evans, D.Litt., LL.D., F.R.S., Oxford, 

 England; Sir Joseph Larmor, D.Sc, LL.D., F.E.S., 

 Cambridge, England; Arthur Schuster, Sc.D., 

 Ph.D., F.R.S., Manchester, England. 



Saturday, April 19 — Moening Session 



Edward C. Pickering, D.Sc, LL.D., F.E.S., 



vice-president, in the chair 



The Potassium, Phosphorus, Nitrogen Cycles: 



Charles E. Muneoe, Ph.D., LL.D., F.C.S. 

 An Ammonia System of Acids, Bases and Salts: 



Edward C. Franklin, M.S., Ph.D. 

 Some Unsolved Proilems in Radioactivity (illus- 

 trated) : William Duane, Ph.D. Introduced 

 by Professor Arthur W. Goodspeed. 

 More than thirty different substances are known 

 to be radioactive in much the same way that ra- 

 dium is radioactive. Most of these substances dis- 

 appear more rapidly than radium does, only five 

 of them having an average life greater than that 

 of radium, which is about 2,000 years. The 

 average lives of the others vary from a fraction 

 of a second to 24 years. 



The law according to which these substances 

 disappear is the same for all of them. It may be 

 stated thus: The rate at which any substance dis- 

 appears is proportional to the quantity of that 

 substance present, and absolutely independent of 

 all conditions of temperature, pressure and state 

 of chemical combination, etc. This is a very 

 simple law, and the mathematical equations that 

 can be deduced from it probably represent the 

 facts as accurately as any known equations repre- 

 sent facts in other branches of science. 



Looked at from another point of view, this law 

 is not very easy to understand. Let us take a 

 particular example. Suppose we have a quantity 

 of that substance called radium emanation. The 

 law applied to this quantity of radium emanation 

 means: that certain atoms of emanation will ex- 

 plode and transform themselves into radium A, 

 during the next few seconds, whereas other atoms 

 of this same emanation will remain emanation 

 atoms for a long time, and will not transform 

 themselves for months to come. The question is 

 this: How can atoms which are physically and 

 chemically similar to each other, yet be so dif- 

 ferent that some of them will disappear imme- 

 diately and others not for a long time. The 

 explanation of this probably lies in the internal 

 structure of the atom and not in external causes, 

 for external conditions have no known effect upon 

 the phenomenon. 



The second unsolved problem to which I wish 

 to call your attention is connected with the rays 

 given off by the substances during their trans- 

 formations. Some substances produce what are 

 called a-rays and some /3-rays, and other substances 

 produce both a- and /3-rays. If a particular sub- 

 stance produces a-rays, one and only one a-particle 

 is ejected during the transformation of each atom 

 of that substance, and the same is true of the 

 /3-rays. The a-particles from the same substance 

 all have the same velocity. For instance, the 

 a-rays from radium C all have a velocity of 

 2.09 X 10°. The /3-rays, however, from the same 

 substance do not all have the same velocity. Each 

 /3-particle has one of a certain number (8 or 10) 

 of well-defined velocities. For example, each /3- 

 partiele projected from an atom of radium C must 

 choose one of a certain set of velocities lying 

 between 1.85 X 10" and 2.99 X 10« cm./sec. 



It is difficult to understand why the explosion 

 of an atom, say of radium C, which, so far as 

 known, is just like the explosion of every other 

 atom of radium C, and produces an a-ray of a 



