370 Report of the Department of Chemistry of the 



stand for 24 hours. The precipitate was filtered off and the filtrate 

 evaporated on the water-bath until the excess of ammonia was 

 driven off. It was then diluted with water and precipitated with 

 barium chloride in excess, filtered and washed and suspended in 

 cold water and decomposed with slight excess of dilute sulphuric 

 acid. After filtering, the filtrate was neutralized with ammonia 

 and again precipitated with barium chloride. These operations 

 were repeated three times and after finally removing the barium the 

 filtrate was precipitated with copper acetate — this was filtered 

 and washed until the filtrate gave no reaction with barium chloride. 

 The copper precipitate was then suspended in water and decom- 

 posed with hydrogen sulphide, filtered and the filtrate evaporated 

 on the water-bath to a syrupy consistency. This syrup was poured 

 into 1,600 c.c. of alcohol and allowed to stand for the precipitate 

 to settle. It was then filtered and again evaporated on the water- 

 bath until the alcohol was removed. The residue was the crude 

 acid which was obtained as a brown-colored syrup. It was diluted 

 with water to 100 c.c. in which it formed a slightly opalescent solution 

 of faint aromatic odor. It was divided into two parts; 75 c.c. was 

 used for the preparation of the barium salt; of the balance, 10 c.c. 

 was used for the preparation of the silver salt. 



PREPARATION OF THE SILVER SALT FROM THE CRUDE ACID. 



The 10 c.c. of the above acid solution was diluted to 100 c.c. with 

 water and ammonia added to alkaline reaction. The excess of 

 ammonia was boiled off, the solution cooled and silver nitrate added 

 which caused a voluminous yellow-colored amorphous precipitate. 

 This was filtered, washed in water and dried in vacuum over sul- 

 phuric acid. The substance was very sensitive to light, and although 

 the desiccator was kept in a dark place the dry salt was very dark 

 in color. 



The filtrate from above was quite acid in reaction. It was neutral- 

 ized with ammonia when a further quantity of a yellowish precipitate 

 came down. More silver nitrate was added and the precipitate 

 filtered, washed and dried as before. This was also a very dark 

 amorphous powder. The precipitates were free from all but traces 

 of ammonia. 



These silver precipitates were analyzed after drying at 105° in 

 vacuum over phosphorus pentoxide. The first precipitate gave: 

 C = 2.18; H = 0.53; Ag = 71.82; total phosphorus = 7.82; inorganic 

 phosphorus = 5.61 per ct. 



The inorganic phosphorus was determined as follows: the sub- 

 stance was suspended in cold water and dissolved by the addition 

 of cold dilute nitric acid and the silver precipitated with hydro- 

 chloric acid. The filtrate was neutralized with ammonia, acidified 

 with nitric acid, ammonium nitrate and ammonium molybdate 



