332 TRANSACTIONS OF THE [jUNE 7, 



The first paper of the evening was by Professor Wm. Hallock 

 in " An Improved Method of Projecting Views of the Moon." 



The paper was discussed by Messrs. Martin, Kemp and 

 Dudley. It will appear in an early issue of Science. 



Miss F. R. M. Hitchcock then read a paper entitled " Notes on 

 the Atomic Mass of Tungsten." 



NOTES ON THE ATOMIC MASS OF TUNGSTEN.* 

 By Fanny R. M. Hitchcock. 



From work previously done the author had reason to think 

 that tungsten was not a simple element. In that case, assuming 

 that the elements composing it had atomic weights which dif- 

 fered considerably among themselves, it should be possible, by 

 fractionating tungstic oxide, to obtain a series of atomic weights 

 for the so-called metallic tungsten which would differ widely from 

 each other. 



In accordance with this idea a series of experiments was made, 

 and a summary of the principal results obtained is given below. 

 Some of the results obtained are not given, as they were so un- 

 expected that it is deemed desirable before publication to repeat 

 the experiments which led to them, as, while there seemed no 

 reason to doubt the results themselves, the conditions under 

 which they were produced are not perfectly understood. 



The methods used in preparing the acid and in fractionating 

 the same will be given together with details of all the work done 

 and a discussion of the same, in a paper to be published as soon 

 as certain investigations now underway are concluded. 



The acid, before fractionating, was tested for and found free 

 from alkalis, alkali earths, aluminum, iron, manganese, silica, 

 columbic, tantalic and molybdic oxides. It was transformed 

 into ammonium salts and fractionated by different methods. 

 The atomic weights of two series of fractions are given below. 

 The acids used in the two series had been subjected previously 

 to different treatment. The quantity of material used at any 

 one time varied from 1.5 to 5 grams. Throughout the whole 



♦Abstract in part of work done by the author |in connection with Dr. Carl Freid- 

 heim, at the Laboratory of Dr. Freidheim and Dr. Rosenheim, in Berlin, Germany, 

 during the year ending April 15, l.s%. 



