PROCEEDINGS OF THE ACADEMY AND AFFILIATED 



SOCIETIES 



WASHINGTON ACADEMY OF SCIENCES 



The Board of Managers met on Monday, March 25, 1918. A 

 majority of the committee appointed at the preceding meeting to 

 consider the project of pubHshing reviews of articles from foreign 

 journals on problems connected with the war reported adversely on 

 the project, principally on account of the lack of editorial facilities for 

 such purposes. A committee consisting of Messrs. Maxon, Knopf, 

 Dorset, Sosman, and Scofield was appointed to offer plans for 

 making the Journal more systematically and equally representative 

 of the different branches of science, and more useful to the affiliated 

 societies. A committee consisting of Messrs. Sosman, Kearney, 

 and Bartsch w^as appointed to confer with the Board of Management 

 of the Cosmos Club on facilities for the scientific society meetings in the 

 new assembly hall of the Club. 



Robert B. Sosman, Correspondi7ig Secretary. 



PHILOSOPHICAL SOCIETY OF WASHINGTON 



The 800th meeting was held at the Cosmos Club, February 2, 1918; 

 Vice-President Humphreys in the chair; 19 persons present. The 

 minutes of the 800th meeting were read in abstract and approved. 



Mr. W. S. Gorton presented a paper on X-ray 'protective materials. 

 The importance of the purpose served by X-raj^ protective materials 

 is generally recognized. A thorough comprehension of the subject 

 involves knowledge of both the physical and physiological properties 

 of X-rays. 



X-rays are generated by the stoppage of cathode rays by matter. 

 They may be classified as soft and hard; synonyms for these terms are 

 "easily absorbed" and "penetrating." It is now known that X-rays 

 are like light waves but of shorter wave length. The penetrating power 

 increases with decreasing wave-length. jVIethods of measuring quahty 

 are as follows: 1, absorption in some substance, generally aluminum; 

 2, parallel spark gap; 3, wave length; 4, Benoist penetrometer. The 

 last device has l3een shown (at the Bureau of Standards) to be of 

 practically, no use with a modern transformer outfit. 



The physiological effects of X-rays may be classified as superficial 

 and deep-seated. The former class comprises X-ray "burns." These 

 burns are due to the absorption of very soft rays by the skin. They 



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