2 SCHMITZ, On a Method of Ice Calorimetry. 



allowed to remain adhering to the external surface of the 

 ice-coating. 



Professor Joly, in a letter to Nature* gave the principle 

 of a gravimetric ice calorimeter in which an object 

 suspended from one arm of a balance is first cooled below 

 o^^C. and then immersed in ice-cold water. Professor Joly 

 kindly allows me to publish the following additional 

 details. The object under experiment is almost com- 

 pletely enclosed within a copper sphere. This sphere is 

 the inner of two concentric spheres, between which the 

 refrigerating material circulates. Outside the outer sphere 

 is a space for water and ice, poured in at the last moment. 

 The spheres are made up of two separate hemispherical 

 portions ; these close on a vertical diametral plane and 

 are held closed, watertight, by screws. A hole through 

 one of the hemispherical portions admits a mercury or 

 platinum thermometer. After the temperature of the 

 substance has become constant, a plug at the base of the 

 pair of spheres is withdrawn and water at o*^C. flows up 

 around the substance from the outer space. An ice-jacket 

 is thus formed upon the object. The weighing is made 

 while the object, with its ice-jacket, remains suspended in 

 the ice-cold water. 



Messrs. Bedford & Green, in a communication to the 

 British Association of I90i,"f gave a preliminary account 

 of a method in which the object under experiment is first 

 placed in a cold chamber for a sufficient time, then carried 

 to a calorimeter containing ice-cold water, and, with its 

 ice-jacket, weighed during immersion. 



Professor Dewar has described | a similar method, but 

 has not published details. 



* Vol. 52, p. 80, 1895. 



t Report, p. 544. 



X British Association, 1903. 



