IODIDE, BROMIDE, AND CHLORIDE OF SODIUM. 213 



remaining in solution because chloride of sodium is 

 present. After the lapse of twelve hours, the precipi- 

 tate is collected upon a weighed filter, dried over oil 

 of vitriol, or at a temperature not exceeding 80, and 

 weighed. 



The excess of palladium in the filtrate is separated 

 by means of sulphuretted hydrogen, in order to pre- 

 vent the formation of a precipitate containing palladium 

 upon the subsequent addition of nitrate of silver. The 

 excess of sulphuretted hydrogen is then removed from 

 the solution by sulphate of sesquioxide of iron, and 

 the filtrate mixed with nitrate of silver, when a pre- 

 cipitate of chloride and bromide of silver is formed, 

 which is collected, washed, dried, and fused. A quan- 

 tity of this precipitate, weighed in a bulb-tube, is fused 

 in a current of dry chlorine until bromine vapor ceases 

 to be evolved, and the tube changes no longer in 

 weight. Before weighing, every trace of chlorine 

 must be removed from the bulb. 



A simpler method consists in pouring water over 

 the weighed mixture of bromide and chloride of silver, 

 adding a few drops of hydrochloric acid, and a frag- 

 ment of zinc. In twenty-four hours the silver is com- 

 pletely reduced; it is rubbed to powder, boiled with 

 water containing hydrochloric acid, afterwards washed 

 with pure water, ignited and weighed. 



The difference between the equivalents of chlorine 

 and bromine is to the equivalent of bromine, as the 

 difference between the amounts of chloride and bromide 

 of silver employed, and the amount of chloride which 

 the reduced silver ought to yield, is to the amount of 

 bromine present. 



Itor example: 200 parts of a mixture of equal 

 weights of chloride and bromide of silver gave, when 

 reduced, 132,73 of silver, which would yield 176.31 of 

 chloride of silver. 



Difference between the equivalents of chlorine and 



