CONTRIBUTIONS FROM THE CFIEMICAL LABORATORY 

 OF HARVARD COLLEGE. 



NEW METHODS OF DETERMINING THE SPECIFIC 

 HEAT AND THE REACTION-HEAT OF LIQUIDS. 



By Theodore "William IIiciiakds and Arthur Becket Lamb. 



Presented Murcli 8, 1905. Received January 27, 1905. 



Table of Contents. 



Introduction 059 



Previous Methods 6G0 



A New Method 663 



Tlie Hot Thermostat 664 



The Cold Thermostiit ..... 668 



The Calorimeter, etc 669 



Page 



The Heat of Dilution 675 



Results 676 



Berthelot's Indirect Method for 



more Dilute Solutions .... 678 

 Summary 679 



Introduction. 



The determination of the specific heats of solutions is a matter of 

 importance, not only, because these values are a necessary part of all 

 thermochcmical calculation, but also because of the probable connection 

 between change of heat capacity and the " bound energy " of a reacting 

 system.* Moreover, the irregular relations apparently existing between 

 the values themselves still lack adequate explanation — and no satis- 

 factory explanation can be given until the facts are more definitely and 

 exactly known. 



These considerations induced us to undertake the study of the problem, 

 and the present paper recounts as briefly as possible the devices which 

 were found to be necessary in order to eliminate the most serious possi- 

 bilities of error. 



The study of the heat capacity of liquids led directly, as will be seen, 

 to a study of the heat of reaction evolved by mixins li(pjid< ; and for 

 this purpose also new devices were found to be serviceable and conducive 

 to precision. Because the two investigations are closely allied, they are 

 given here together. 



* Richards, These Proceedings, 38, 293 (1902) ; Van't HofE, Drude's Annalen, 

 Boltzmann. < 



