TRANSACTIONS OF SECTION B. 



543 



To obtain further data, to find how much of the heat given as combiniDfr Iioat 

 of elements is due to pliysical chanjre, I }iiive as a lirst step constructed a special 

 heating: njjparatiis and a calorimeter for determining specific heats, solid and liquid, 

 and latent heat of fusion of high temperatures. 



In my apparatus I have used various salts in a large platinum crucible as a 

 bath for obtaining a steady high temperature. The platinum crucible containing 

 the salt was licated inside an iron cylinder. 



The weighed quantity of salt whose heat capacity was to bo measured, was 

 contained in a platinum capsule formed from two platinum cylinders, each closed 

 at one end. This capsule was dropped into a long platinum tube with arms. As 

 soon as the salt in the salt bath is melted the tube with capsule -was inserted in 

 the liquid, and allowed to remain twenty minutes, which time was found sufficient 

 to bring the contents to the temperature of the bath. 



The gas under the salt bath was then turned out, and while cooling the salt 

 kept well stirred by moving the platinum tube. The tube is not withdrawn till 

 the salt in salt bath becomes viscous. The tube is then taken out and overset so that 

 the capsule drops into the calorimeter ; the temperature of capsule and contents 

 then being the temperature of the solidifying point of the salt bath, which, if NaCl. 

 was 772°; KCl, 734°; CaCh, 719°. 



The calorimeter contained a bell-mouthed long silver tube into -which the cap- 

 sule dropped, and in the lower part of which it fitted moderately closely. 



This tube was fitted on a silver wire stand in a long cylindrical silver vessel 

 which contained 500 grammes of water. A long silver wire rising out of the 

 calorimeter was the means of moving a broad silver ring up and down the outside 

 of the tube, and so kept the water well stirred. 



The silver vessel was suspended by silk thread in a copper vessel silvered on the 

 inside. This copper vessel was placed in the centre of a second copper vessel of 

 about two centimetres larger diameter. Tlie interspace between tliese two vessels 

 was filled with water. The second copper vessel was surrounded by a third, the 

 interspace being packed with swansdown. 



The thermometers used were two feet long, graduated nine inches from the 

 bottom of the bulb lo° C, and rising to 30°. Thedegi-ees were graduated into -05, 

 and could be read with ease correctly to 'Ol. 



The results obtained are shown in the following table. 



Table I. 



(The figures for the heat in this table represent calories given by 1 gramme of 

 ih salt.) 



each salt.) 



