BROMINE IN SEA AVATER. 



91 



after a certain intensity has been obtained, but not the de- 

 crease. Tlie record of "addition allowed to the whole" 

 ought to be based on certainty, which may be won by an- 

 other fractional titration. The following table will explain 

 how the titration ought to have been made : 



etc., like No. 2 of the foregoing table. 



To sum up, this kind of titration is based at the begin- 

 ning on coloration, and toward the finish on decoloration, of 

 the fraction in the cup. As long as three drops are re- 

 quired tojproduce a decoloration, another fractional titra- 

 tion may be safely undertaken; but when already two drops 

 change the color decidedly, it is better to stop and proceed 

 to the final test with chloroform. These remarks refer, of 

 course, only to a standard solution of about the strength 

 indicated here. 



