Section 63. Conductance-Capacity. 159 



dish in a slow current of dry air at 105. The loss of weight became con- 

 tinuous and quite uniform being due doubtless to vaporization of the salt. 

 A nearly 0.1 normal solution was made by weighing out the salt and dis- 

 solving in a weighed quantity of water. The exact content was 93.56 

 millimols per kilogram solution, and this agreed closely with the content 

 (93.64) determined as a check by precipitation with silver nitrate.* In 

 most of the experiments with this salt about $ an equivalent of ammo- 

 nium hydroxide for each equivalent of salt was added, in order to make 

 the hydrolysis inappreciable. The ammonium hydroxide solution used 

 for this purpose was a fourth one, about 0.1 normal, freshly prepared from 

 the strong ammonia ; its conductance was about the same as that of the 

 other solutions when freshly prepared. 



A stock solution of ammonium acetate, approximately 50 milli-normal, 

 was prepared by mixing a definite weight of ammonium hydroxide solu- 

 tion (No. 3), with that weight of an approximately 100 milli-normal 

 acetic acid solution which contained a quantity of the acid exactly equiva- 

 lent to the base. This acetic acid solution was made by diluting with 

 water of specific conductance 0.8 X 10~ 6 glacial acetic acid purified by 

 fractional freezing and by distillation. It was standardized, using phen- 

 olphthalein as an indicator against a barium hydroxide solution which had 

 been titrated against the hydrochloric acid solution last referred to. The 

 exact concentration of this acetic acid solution was 105.58 milli-equivalents 

 per liter at 4 (105.44 at 18) and its equivalent conductance (not cor- 

 rected for the conductance of the water) was 4.57. The value obtained 

 by Noyes and Cooper (interpolated by the equation A 2 C = const.) for this 

 concentration was 4.55, in as good agreement as could be expected with 

 entirely independent samples and solutions. 



63. THE CONDUCTANCE-CAPACITY OF THE APPARATUS. 



The conductance-capacity of the bomb was determined by measuring 

 the actual conductance at 17.93 of 0.02 and 0.01 normal potassium chlor- 

 ide solutions prepared by dissolving 1.4910 or 0.7455 gm. of salt (weighed 

 in air) in one liter of water (of conductivity 0.7-0.9 X 10" 6 at 18) at 

 18, and dividing this after correcting for temperature and conductance 

 of the water into the specific conductances of these solutions (2399 

 or 1224.3 X 10 -6 ) corresponding to the equivalent conductances at 18 

 given by Kohlrausch and Maltbyf (119.96 or 122.43). 



*As shown by the following data : 



Solution taken (grams). 89.51 98.64 122.61 



AgCl obtained (grams). 1.2030 1.3250 1.6481 

 Millimols per kilogram. 93.74 93.69 93.75 



The mean is 93.73 or when the weights are reduced to vacuo it becomes 93.64. 

 fLandolt-Bornstein-Meyerhoffer, Tabellen, 744 (1905). 



