160 CARNEGIE INSTITUTION OF WASHINGTON. 



combination. Several forms of silica, whose expansion is very small, and 

 which therefore practically give values of specific heat at constant volume, 

 Cv, show that Cv for high temperatures exceeds the theoretical value 5.96. 

 Glasses show, in the main, a specific heat only shghtly above the correspond- 

 ing crystal forms, but with a tendency to increase at some rather high tem- 

 perature. In several sets of polymorphic forms with sluggish inversions there 

 were differences of about 2 per cent between the two forms, but none of these 

 forms showed any variation in specific heat near the inversion temperature. 

 In quartz, below the a-jS inversion at 575°, the heat absorption is greater 

 than can be accounted for even by the abnormal expansion. If such absorp- 

 tion, unusual change of volume, and change of crystal properties are each or 

 all together the sign of a change of state, then quartz undergoes a gradual 

 change of state over an interval of 400° below what is commonly called its 

 a-0 inversion. Quartz, and probably other forms of silica, exhibit what 

 appear to be two kinds of inversion, due to different mechanisms. 



Some of these facts mihtate against certain hypotheses which make poly- 

 morphism the resultant of polymeric or isomeric changes in the soUd. 



(6) Specific heat determination at higher temperatures. Walter P. White. Am. J. Sci., 



47, 44-59 (1919). 



This paper deals with the experimental technic of specific heat determina- 

 tion at temperatures up to 1400° by the "method of mixtures," and con- 

 tinues some earher presentations. Detailed modifications 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. 



(7) The thermal dissociation of sulfur dioxide. J. B. Ferguson. J. Am. Chem. Soc, 



41, 69-72 (1919). 



The degree of dissociation and the equilibrium constants for the dissociation 

 of sulphur dioxide have been calculated from the equihbrium measurements 

 of the reduction of sulphur dioxide by carbon monoxide and the dissociation 

 of carbon dioxide, and the results of these calculations for a number of tem- 

 peratures and pressures are given in this paper. The values obtained con- 

 firm the experimental results, which indicated that the dissociation was too 

 slight to be directly studied by the present available methods. 



(8) The determination of the compressibility of solids at high pressures. Leason H. 



Adams, Erskine D. Williamson, and John Johnston. J. Am. Chem. Soc, 41, 

 12-42 (1919). 



The change in volume of a solid under the influence of pressure is rarely 

 greater than a few parts per milhon for each atmosphere change of pressure. 

 It is therefore not surprising that the measurement of the volume-change of 

 soHds as affected by pressure should offer pecuUar difficulties, quite apart 

 from those inherent in high-pressure experimentation, and that the published 

 records contain very few measurements on the compressibility of solids under 

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

 change under pressure of a sohd may be determined with an accuracy of about 

 1 part in 10,000 of the original volume of the solid; that is, the volume- 

 change for a range of 10,000 kg. per sq. cm. is determined with an accuracy 

 of 10 -8 per kg. per sq. cm. Results are presented for the metals gold, cop- 

 per, silver, aluminum, zinc, tin, cadmium, lead, and bismuth; for the alloys 

 brass and tin-bismuth eutectic; and for sodium chloride, calcium carbonate, 

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

 12,000 megabars (1 megabar = 0.987 atm.). In carrying out the determina- 



