280 MORRIS LOEB 



remained practically constant for many hours, when enclosed 

 in a circuit of 5000-10,000 ohms resistance. It also had the 

 advantage of being always ready for use. 



3. PREPARATION OF THE SILVER SOLUTIONS 



The solutions of argentic nitrate were prepared from the 

 crystallized salt. Those of the chlorate, perchlorate, ethyl- 

 sulphonate, naphthalene-sulphonate, benzene-sulphonate, 

 pseudo-cumene-sulphonate and acetate, were made by neu- 

 tralizing known amounts of these acids with moist argentic 

 oxide, passing the solution through an asbestos filter, and 

 diluting to a suitable volume. Argentic dithionate (Ag 2 S 2 O 6 ) 

 was obtained by the reaction of exactly equivalent quantities 

 of baric dithionate and argentic sulphate. To make ar- 

 gentic fluosilicate, a solution of hydrofluosilicic acid was 

 saturated with argentic oxide; dilute baric hydrate solution 

 was then added cautiously, until the brown color of argentic 

 oxide commenced to appear in the precipitate of baric fluo- 

 silicate. The neutral solution was then filtered and diluted. 



4. DESCRIPTION OF A DETERMINATION IN DETAIL 



The description of this determination, made with a solution 

 of argentic nitrate which was about ^ normal, will best 

 illustrate our method of experiment and calculation. The 

 electrolysis was [112] conducted at a temperature of 26, and 

 the solution thereupon divided into four portions, which are 

 numbered in the following table in the order in which they 

 were taken out; consequently, No. 1 represents the lowest 

 stratum in the apparatus. Column I contains the weights of 

 these portions; II, the amount of silver found in each; III, 

 the amount each portion would have contained if no change 

 had occurred, estimated from the fact that 1 gram of the 

 solution originally contained 1.139 milligram of silver. 



