CHEMISTRY — RICHARDS. 219 



Richards, Theodore W., Harvard University, Cambridge, Massachusetts. 

 Grants Nos. 524, 570, and 626. Extended investigations of precise 

 values of atomic weights; and a study of volume and energy relative to 

 material in relation to the nezv hypothesis of compressible atoms. (For 

 previous reports see Year Books Nos. 2-8.) Each grant, $2,500 



(i) The Revision of the Atomic Weight of Calcium: 



With the help of Dr. Otto Honigschmid, upon leave of absence from the 

 Royal German University of Prague, a careful research was completed upon 

 the atomic weight of calcium. This element is especially interesting, not 

 only because it is one of the very common and important constituents of the 

 surface of the globe, but also because it is one of the interesting series of 

 which radium is the last and newest member. The atomic weights of barium 

 and strontium, the other members of this series, have been determined with 

 care in the Chemical Laboratory of Harvard College, and that of calcium 

 was begun 15 years ago, but only preliminary determinations were made at 

 that time. It was very highly desirable, therefore, to complete this work. 

 Dr. Honigschmid analyzed with great care many pure specimens of calcium 

 bromide and chloride made in different ways from the purest materials, with 

 all the precautions recently devised in this laboratory, and obtained the fol- 

 lowing final average results, if silver is given the present international value, 

 107.88 : 



From the ratio 2Ag :CaBr2 (6 analyses) Ca=40.070 



ratio 2AgBr :CaBr2 (6 analyses) Ca=40.o7o 



ratio 2Ag : CaCls (7 analyses) Ca=40.074 



Average of 19 analyses Ca=r40.07i 



Not only the averages, but also the individual results, agreed very closely 

 with one another. 



The outcome leaves no doubt that the atomic weight of calcium is not far 

 from 40.07, a result only slightly lower than that given by the preliminary 

 Harvard investigations (40.08), but much lower than the value, 40.15, ob- 

 tained by Hinricsen under Landolt's direction in Berlin. 



This work will appear among the publications of the Imperial and Royal 

 Academy of Sciences of Vienna as well as in the usual American publications. 



(2) The Revision of the Atomic Weights of Lithium, Chlorine, and Silver: 



This investigation, concerning which a comprehensive paper was published 

 in Publication No. 125 of the Carnegie Institution of Washington and re- 

 printed in the Journal of the American Chemical Society and the Zeitschrift 

 fiir Anorganische Chemie, has been continued yet further during the present 

 summer, Dr. H. H. Willard having returned to Harvard from the University 

 of Michigan for the summer months on this account. The work is being 

 conducted with the yet greater precision made possible by experience gained 

 in the work already published, and the operations are being conducted upon 

 a somewhat larger scale. The earlier results are confirmed. Evidence is to 



