220 REPORTS OF INVESTIGATIONS AND PROJECTS. 



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

 Grants Nos. 524 and 570. Extended investigations of precise values of 

 atomic weights and other physico-chemical constants; and a study of 

 volume and energy relative to material in relation to the new hypothesis 

 of compressible atoms. (For previous reports see Year Books Nos. 2, 

 3, 4, 5, 6, and 7.) Each grant, $2,500. 



During the academic year 1908-09 portions of these grants were used in 



the completion of five researches and the beginning of several others, as 



follows : 



I. The Revision of the Atomic Weights of Lithium, Chlorine, and Silver: 



With the help of Dr. H. H. Willard, upon leave of absence from the Uni- 

 versity of Michigan, a comprehensive research was continued and essentially 

 completed, involving several important atomic weights. The object of this 

 research was to secure a better comparison than has ever yet been made 

 between the atomic weights of oxygen and silver. The need of the compari- 

 son is due to the fact that whereas oxygen is the standard of atomic weights, 

 most elements are, as a matter of fact, referred either directly or indirectly 

 to silver. The first step in this research consisted in a study of the proper- 

 ties of all the compounds of oxygen which might be used for the purpose, 

 and for many reasons lithium perchlorate was chosen as the most suitable 

 substance for investigation. The precise quantitative study of this substance 

 involved the evaluation of the atomic weight of lithium as well as of all the 

 other elements concerned, and accordingly this determination formed the first 

 step in the work. The methods used were so similar to those discussed in 

 Publications 28 and 69 as to render repetition unnecessary. It was proved 

 beyond doubt that Stas's value for the atomic weight of lithium was almost 

 I per cent in error and that the true value is not far from 6.94. Lithium 

 chloride was then changed into lithium perchlorate in suitable quartz appa- 

 ratus with every quantitative refinement. Because the original salt had al- 

 ready been referred to metallic silver, it is clear that this determination gives 

 at once the ratio 



Ag:4(0) 



If, as is probable, the perchlorate fused at 300° is essentially free from 

 water, the atomic weight of silver is shown by these results to be not far 

 from 107.87 — an interesting and important confirmation of other recent work 

 upon this subject. The question as to whether or not a trace of water 

 remains in the perchlorate will be answered in the near future. 



II. Adiabatic Determination of the Heats of Solution of Metals in Acids: 



With the help of Dr. L. L. Burgess the heat evolved by the action of the 

 more electro-positive among the heavy metals was studied with great care, 

 the object being to secure precise data for thermochemical and thermody- 



