December 17, 1915] 



SCIENCE 



849 



occupied by the atoms. In the interpreta- 

 tion of all the facts, knowledge of the com- 

 pressibility of elements and compounds is 

 essential; and as the available data are 

 scarce, work in this direction was prose- 

 cuted with vigor. It is enough to say that 

 the compressibility of over a score of or- 

 ganic substances and of nine elements 

 (namely, tungsten, molybdenum, tantalum, 

 boron, copper, iron, lead, thallium and 

 mercury) have been determined during the 

 last three years, either for the first time or 

 at least with more accuracy than ever be- 

 fore. The apparatus for this purpose has 

 been studied with a view to the detection of 

 all the insidious minor errors which may 

 affect work of this kind, and has been dis- 

 tinctly improved in several ways. Some 

 of the theoretical outcomes of this work, 

 which shows that the compressibilities of 

 the elements are periodic, like their atomic 

 volumes, have been briefly expounded in the 

 July number of the new Proceedings of 

 this academy. Here it is shown that the 

 compressibility of the elements seems to de- 

 pend in a large degree upon the atomic 

 volumes and melting points of the several 

 elements. 



A revision of thermochemical data, which 

 has been in progress for a number of years, 

 has been especially advanced during the 

 last three years in the "Wolcott Gibbs Memo- 

 rial Laboratory. The method of protecting 

 a calorimeter from accidental heating or 

 cooling, by always keeping the jacket 

 around it at just the same temperature as 

 the calorimeter itself, has been found effi- 

 cient and convenient. Automatic contriv- 

 ances called "synthermal regulators" for 

 maintaining this identity of the two tem- 

 peratures have been devised, and in vari- 

 ous details the ealorimetric procedure has 

 been perfected. This method, by the way, 

 which as applied to calorimeters of chang- 

 ing temperatures took its origin at Harvard, 



is spreading rapidly over the world, and 

 has now adherents not only in various parts 

 of America, but even so far away as 

 Moscow. 



The heat given out by the combustion of 

 many organic substances has been studied, 

 especial emphasis having been laid upon 

 the danger of incompletely burning the 

 more volatile compounds, which evaporate 

 too quickly to be burned all at once; and 

 precautions have been perfected for pre- 

 venting this error. In addition, methods 

 for determining the heat evolved during 

 the solution of metals in acids, the neutrali- 

 zation of acids and alkalies, as well as for 

 finding the specific heats of solutions — data 

 which form the basis of all the thermo- 

 chemistry of metallic salts — have been im- 

 proved and amplified. In connection withi 

 these researches upon the heat evolved in' 

 chemical action, a study of methods of 

 calibrating thermometers, of determining 

 fixed points upon them by the transitioS 

 temperatures of pure salts, and of sub- 

 dividing the intervals between the fixed 

 points in various ways so as to correspond 

 exactly to the true temperature scale, has 

 been carefully conducted. Also, consider- 

 able time was spent upon the further inves- 

 tigation of floating equilibrium — the point 

 at which a sunken sealed float of fixed 

 volume neither rises nor sinks in a liquid. 

 The effect of concentration of various solu- 

 tions on the temperature of this equilibrium 

 was studied, as well as the slight volume 

 changes suffered by the float with time, 

 temperature and pressure. It has been 

 shown that with due care this phenomenon 

 may be used for either analyzing solutions 

 or standardizing thermometers. 



An interesting physico-chemical problem 

 connected with the study of transition tem- 

 peratures is the effect upon the crystalline 

 "melting points" of impurities which 

 crystallize out with deposited salts. In par- 



