APPARATUS AND METHODS. 



9 



a narrow tube, C, which drops, curves upon itself, and rises past the 

 side of the jacket to near the top of the central tube. The upper end 

 of the tube C is enlarged into the cup D. These three parts, A, B, and 

 C (with D), are the essential constituents of Bunsen's calorimeter. 

 The body (B) of the instrument is filled with water above and 

 mercury below, the mercury filling also the arm at the side and rising 

 into the cup at the end of 

 the arm. (See fig. 1.) 



After partially freezing 

 the water Bunsen packed 

 this instrument in clean 

 snow and attached a capil- 

 lary glass tube to the top of 

 C through a cork stopper. 

 Then he noted, by the reces- 

 sion of the mercury menis- 

 cus in the capillary tube, 

 the change in volume pro- 

 duced by the introduction 

 of heat into the tube A. 

 Bunsen's instrument was 

 much smaller than the one 

 used in these experiments. 

 With it he determined the 

 specific heats of calcium, in- 

 dium, ruthenium, and zinc, 

 using about one gram of 

 material in each case. 



Two modifications have 

 been used in the present in- 

 strument. The first is the 

 substitution of the reading 

 arm, E (see fig. 1), for the 

 capillary tube, which showed 

 directly the contraction of 

 the contents of the calo- 

 rimeter. This reading arm l 

 consists of an extension of 



the arm C by which it is FIG. l.-The ice calorimeter and ice jacket in vertical section. 



possible to establish and interrupt connection between the mercury 

 in the calorimeter and that in a vessel, F, suitable for weighing. 

 The vessel of mercury is weighed, and then connection between the 

 mercury in the vessel and that in the calorimeter is established 



i First described by Schuller and Wartha in 1877. Schuller, A., and Wartha, V. Calorimetrische 

 Untersuchungen. Wied. Ann. II, pp. 359-383. 1877. 



