Ludeking and Starr — Specific Heat of Ammonia. 201 



the results of our work. The liquid ammonia used in the 

 experiments was found on examination to contain 0*3 per cent 

 of moisture and on spontaneous evaporation to leave only a 

 trace of residue. The impurities were therefore of no conse- 

 quence in influencing the result to the limit of accuracy 

 intended. 



Of this liquid ammonia 10*01 grams were introduced into a 

 small steel cylinder of 16*122 cc capacity, stoppered by a steel 

 screw. The mode of filling was quite simple. After cool- 

 ing the cylinder in a bath of the liquid ammonia itself and 

 while still immersed it was possible to pour it brimful by 

 means of a beaker. The steel screw stopper, also previously 

 cooled, was then inserted and drawn almost tight. On then 

 removing the cylinder from the cooling bath the liquid con- 

 tents gradually expanded and escaped in quantity proportional 

 thereto and besides a very small vapor space was allowed to 

 form as is indicated in the experimental data. Then the stop- 

 per was driven tight. Thus the error in the result, due to the 

 latent heat of condensation of vapor of ammonia in the 

 course of the experiments was reduced to a minimum and 

 rendered, as will be seen, almost inappreciable in its influence. 



The cylinder was perfectly free from leakage and remained 

 constant in weight during each series of determinations. It 

 was suspended in the drum of a Regnault apparatus heated by 

 the vapor of carbon disulphide. The entire mode of pro- 

 cedure was in all details that commonly used in the E-egnault 

 method. After the cylinder had been heated for about six 

 hours it was dropped into a brass calorimeter whose water 

 value was 1*3 6 cal. and which contained 150 grams of water. 

 In each experiment it required very nearly two minutes to 

 raise the calorimeter to its maximum temperature. The influ- 

 ence of loss by radiation was reduced to a minimum by the 

 Rumford manipulation. The thermometers used were stan- 

 dardized, carefully compared and read to hundredths of a 

 degree by means of a magnifying lens. The experiments 

 were conducted sufficiently far from the critical temperature, 

 which, according to Yincent and Chappuis is 131° C. 



The following are the data of Experiment I : 



Weight of steel cylinder and ammonia 81*00S grams. 



Weight of steel cylinder 70-998 " 



Weight of ammonia 10*01 



The specific gravity of liquid ammonia being 0*656, the 

 volume of 10*01 grams is 15*26 cc . 



