BAXTER. — ATOMIC WEIGHT OF IODINE. 



79 



investigation. Sample B was prepared from silver nitrate which had 

 been recrystallized seven times from nitric acid, five times from water, 

 and finally precipitated by ammonium formiate.* Sample C was pre- 

 cipitated as silver chloride once, electrolyzed once, and finally precipitated 

 with formic acid. All three samples were fused in a current of hydro- 

 gen on a lime boat. In order to determine whether an even more gradual 

 addition of silver nitrate would influence the extent of the occlusion, in 

 Analysis 23 the silver was introduced by means of a large funnel provided 

 with a fine spout. 



TABLE II. 



Series IV. Ag : I. 



In one of the foregoing analyses the attempt was made to determine 

 the ratio between iodine and silver iodide by adding an excess of silver 

 nitrate and weighing the precipitate. Although only five milligrams ex- 

 cess of silver nitrate were added, and the total volume of the liquid was 

 over two liters, the precipitate was one milligram heavier than it should 

 have been as calculated from the result of the titration, showing that the 

 occlusion of silver nitrate by the silver iodide may take place even after 

 precipitation. In order to avoid this difficulty, in succeeding analyses 



* Richards and Wells, Publications of the Carnegie Institution, No. 28, 19. 



