November 21, 1902.] 



SCIENCE. 



825 



request is to endeavor to secure an approxi- 

 mate estimate of the number of scientific men 

 in attendance at the Convocation Week meet- 

 ings in Washington. 



Officers of the local committee for the 

 Washington meeting are: 



President, Charles D. Walcott. 



Y ice-President, G. K. Gilbert. 



/Secretary, Marcus Benjamin. 



Executive Committee, Marcus Benjamin, David 

 T. Day, G. K. Gilbert, Gilbert H. Grosvenor, L. 0. 

 Howard, George M. Kober, W J McGee, C. E. 

 Munroe, Chas. D. Walcott. 



THE AMERICAN PHYSICAL SOCIETY. 



The autumn meeting of the American 

 Physical Society was held at Columbia Uni- 

 versity on Saturday, October 25. 



As has so often been the case in the past, 

 the program was considerably more extended 

 than was to be expected from the printed list 

 of papers distributed before the meeting. 

 Owing to some cause which it seems hard to 

 explain, the titles of papers are frequently — 

 I might ahnost say, usually — sent in too late 

 for publication in the preliminary program. 

 This fact cannot fail to have its effect, both 

 on the discussion of the papers presented and 

 on the attendance at the meeting. It is 

 especially unfortunate for members residing 

 at a distance, for whom attendance at the 

 meeting means a considerable sacrifice of time. 



The first paper presented was by A. W. 

 Ewell on ' Accidental Rotatory Polarization.' 

 Mr. Ewell had found in earlier work that cer- 

 tain jellies when subjected to twist are 

 brought into a condition which enables them 

 to rotate the plane of polarization of light 

 traveling parallel with the axis of twist. The 

 present paper described exiseriments along the 

 same line. The direction of optical rotation 

 was found to be opposite to the direction of 

 twist. The amount of rotation is very largely 

 influenced by stretching or compressing the 

 piece of jelly in question in the direction of 

 the axis of twist. Mr. Ewell finds also that 

 the rigidity of jelly, like that of rubber, is 

 greatly increased by elongation. Upon this 

 fact he bases an explanation of the observed 

 optical rotation. Since the strain is greater 



at points more distant from the axis, the 

 rigidity varies according to the distance from 

 the axis. A corresponding change in the 

 optical rigidity would account for the results. 



A paper by Carl Barus gave the results of 

 some preliminary experiments on the ' Varia- 

 tion of Atmospheric Nucleation ' and its de- 

 pendence upon weather conditions. The 

 method employed consisted in producing con- 

 densation by sudden expansion and in observ- 

 ing the size of the corona formed in the re- 

 sulting mist. Previous investigations of 

 Professor Barus have made it possible to com- 

 pute the diameter of the individual droplets 

 from the diameter of the corona. A measure- 

 ment of the weight of all the mist formed in 

 a given space thus makes it possible to com- 

 pute the number of droplets and therefore 

 the number of nuclei. Observations by 

 means of this method were made several times 

 a day for a period of some weeks. The effect 

 of rain in clearing the atmosphere from nuclei 

 was clearly shown. Professor Barus also 

 pointed out other connections between the 

 amount of nucleation and the weather condi- 

 tions, but he regarded more extended observa- 

 tions as needed before definite conclusions 

 could be reached. 



A paper by George B. Pegram described 

 some very interesting results obtained by the 

 ' Electrolysis of Radioactive Substances.' In 

 the case of thorium salts it was found that 

 the anode acquired a relatively intense radio- 

 activity, which, however, lasted for only a few 

 hours. The kathode, in the electrolysis of 

 thorium salts, showed scarcely any acquired 

 activity. In the case of salts containing 

 radium, however, both anode and kathode 

 became very active after the current had 

 passed for a few minutes. As a result of 

 electrolysis the dissolved salts seemed rapidly 

 to lose their power of imparting this radio- 

 activity to the electrodes; after long-con- 

 tinued electrolysis with one pair of electrodes 

 the effect produced upon new electrodes was 

 very slight. 



A note by Ernest Blaker described a substi- 

 tute for a smoke film which has several ad- 

 vantages. A layer of a white powder could 

 be readily formed upon glass by rubbing it 



