270 H. 1. Cole — Estimation of Iodine and Bromine 



in 



graduate and reading the volume while still warm. For the 

 "final experiments, therefore, an apparatus (shown in fig. 2) 

 was devised which permits more exact reading of the volumes. 

 A tubular flask 25-6 cmS high and 3'2 cm in diameter with a 

 capacity of 150 cmS , and provided with a ground-glass stopper 

 and delivery tube extending to the bottom of the flask, was 

 substituted "for the distillation flask. Etched lines at l cm3 in- 



Fig. 2. 



tervals in the locality of final volumes furnished a very accurate 

 and simple means for determining the concentrations. An 

 asbestus collar wound with nichrome wire (offering a resistance 

 of 16 ohms) was used on a 110 volt current (with a 12 bulb 

 lamp-board) as a means for heating, and was lowered on the 

 flask as the solution evaporated. Steam was passed in at such 

 a rate that the solution never became highly colored with the 

 liberated halogen. A series of tests, 'Table III (A),' shows 

 that all the bromine eliminated from 0*5 grm. of potassium 

 bromide can be removed by concentrating from a volume of 

 TO " 8 to a volume of 28 cm3 -25 cm3 with the aid of steam. 



