352 CARNEGIE INSTITUTION OF WASHINGTON. 



7. Further Study of the Compressibility of the Elements. 



With the help of Mr. E. P. Bartlett, the study of the compressibiHty 

 of the elements was continued. Through the courtes}^ of Dr. Whitney, 

 of the General Electric Company, fine specimens of tungsten, molyb- 

 denum, and tantalum were lent to us for the purpose of determining 

 their compressibility, and the constants concerning these elements were 

 determined for the first time. They take precisely the expected places 

 in the curve which was the outcome of the earlier Harvard work sub- 

 sidized by the Institution. Tungsten has the smallest compressibility 

 of any metal thus far investigated, as would be expected from its 

 exceptionally low volatility. In order to obtain results of the degree 

 of accuracy desired, a new steel piezometer (upon the principle of the 

 glass ones already used in the Harvard work) was constructed and 

 found to yield results much freer from hysteresis-effects than the glass. 

 Not only were these metals determined for the first time, but also the 

 commoner elements, such as mercury, copper, iron, and lead, were 

 studied with a degree of precision not heretofore obtained, and several 

 liquids, among them the liquid amalgams of thallium, were likewise 

 subjected to careful investigation. 



8. A New Study of the Surface Tension of Liquids. 



In keeping with the plan to study and compare all the important 

 physical properties of typical substances, a new study of the surface 

 tension of liquids was begun with the help of Mr. L. B. Coombs. The 

 tubes in which the levels were compared were subjected to unusual 

 scrutiny and the apparatus was so arranged that readings might be 

 made both in the erect and inverted position as well as from both sides, 

 so that irregular refraction of the glass (which turned out to be a much 

 more serious cause of error than is usually suspected) was effectually 

 eliminated. A number of homologous organic liquids were studied 

 and the results await comparison with the heats of combustion, boiling- 

 points, densities, and other properties now in the process of investiga- 

 tion at this laboratory. 



9. Dielectric Constants. 



With the help of Dr. J. W. Shipley, the dielectric constants of many 

 of these liquids were studied ; and the method of Nernst was improved 

 and made more sensitive for this purpose. Various other properties 

 also, such as boiling-points and melting-points, received careful con- 

 sideration, and with the help of our accurate temperature scale these 

 were fixed with a degree of precision not heretofore obtained. Among 

 other substances, benzene was obtained from manj^ sources and very 

 carefully purified. Its melting-point was found to be 5.484° C, and 

 it is recommended in connection with the melting-point of ice as a very 

 convenient second temperature for standardizing Beckmann ther- 

 mometers. 



