598 abstracts: physics 



before deciding on the one to be used as the basis for the grid tables. 

 The Lambert projection, which was used in France, was not apphcable 

 to the United States because of the great range in latitude in this 

 country. 



The publication contains examples of the transformation of the 

 geographic to grid coordinates and the reverse. While the tables were 

 computed especially for use in the construction of military maps in 

 the United States, it is possible that the system may sometime be used 

 on maps for civil purposes. W. B. 



PHYSICS. — Specific heat determination at higher temperatures. Wal- 

 ter P. White. Amer. Journ. Sci. 47: 44-59. January, 1919. 

 This paper deals with the experimental technic of specific heat 

 determination at temperatures up to 1400° by the "method of mix- 

 tures," and continues some earlier presentations. Detailed modifica- 

 tions in furnaces and in methods of transferring to the calorimeter are 

 described. The heat losses attending the dropping of hot bodies into 

 water proved to be surprisingly large; their prevention is probably 

 advisable in accurate work, perhaps by the use of aneroid calorimeters. 



W. P. W. 



PHYSICS.— r/i^ determination of the compressibility of solids at high 

 pressures. L. H. Adams, E. D. Williamson, and John Johnston. 

 Journ. Amer. Chem. Soc. 41: 12-42. January, 19 19. 

 This paper describes a method by means of which the volume- 

 change under pressure of a solid may be determined with an accuracy 

 of about one part in 10,000 of the original volume of the solid. 

 Results are presented for the metals gold, copper, silver, aluminum, 

 zinc, tin, cadmium, lead, and bismuth; for the alloys brass and tin- 

 bismuth eutectic; and for sodium chloride, calcium carbonate, and 

 silica, both crystalline and amorphous. The pressure range was 2,000 

 and 12,000 megabars (i megabar = 0.987 atm.). The P — AF graphs 

 which show the relation between volume-change and pressure were 

 found to be nearly straight lines; however, the more compressible 

 metals exhibit a slight but unmistakable curvature such that the 

 graphs are concave toward the pressure axis. From this curvature a 

 rough estimate was obtained of the change of compressibility between 

 o and 10,000 megabars of all the solids examined (except gold, copper, 

 silver, aluminum, and brass, for which the compressibility is inde- 

 pendent of pressure within the error of experiment). L. H. A. 



