272 H. I. Cole — Iodine and Bromine in Haloid Salts. 



0*25 grin, of chlorine combined in the form of chloride (0*5 

 grm. of potassium chloride). 



According to the procedure found to be effective, the three 

 haloid salts are introduced into the tubular flask with 50 cn ' 3 of 

 water. The flask and the inlet tube of the receiver, the latter 

 charged with 200 cm3 of a 1*5 per cent solution of potassium 

 iodide, are connected after moistening the surface of the 

 ground-glass joint. Telluric acid, 1 grm., dissolved in 

 15 cmS of sulphuric acid, sp. gr. 1*015, measured from a burette 

 is introduced through the separating funnel with sufficient 

 water to make the volume 100 cm3 . Carbon dioxide and steam 

 are passed very slowly through the solution and the boiling 

 mixture is not allowed to concentrate below 100 rm3 until all 

 traces of color due to liberated iodine has left the solution. 

 The mixture is then evaporated, with only enough steam to 

 prevent the return of any color, to a volume of 64 cm3 to 67 cm3 . 

 The amount of heat is regulated by the lamps in the resistance 

 board and the furnace is always kept just below the surface of 

 the solution in the tubular flask. At the final volume the 

 source of heat is withdrawn and as soon as the apparatus is 

 cool enough to be conveniently handled the receiver is discon- 

 nected and the free iodine in the receiver and trap is titrated 

 with standard sodium thiosulphate. The receiver is then again 

 charged with 200 cm3 of 1*5 per cent potassium iodide solution 

 and connected after moistening the surface of the ground-glass 

 joint with sulphuric acid to serve as a lubricant and lute. 

 Sulphuric acid, 10 cm3 of the [1 : 1] mixture, is introduced 

 through the separating funnel and carbon dioxide is passed 

 very slowly through the apparatus. As soon as the boiling 

 mixture shows any discoloration steam is passed in at a rate 

 just sufficient to compensate for the vapor carried over until 

 all color is removed, when the concentration is slowly con- 

 tinued with the help of steam to a volume of 30 cm3 , from which 

 point the remaining solution is rapidly boiled to a volume of 

 24 cm3 . The furnace is removed and, as soon as the apparatus 

 is sufficiently cool to disconnect, the free iodine in the receiver 

 and trap is titrated with standard sodium thiosulphate and 

 taken as the measure of the bromine liberated. 



By the procedure described it is possible to determine with 

 a good degree of accuracy any amount of iodine or bromine up 

 to 0*3 grm. when associated in the haloid salts with amounts of 

 chlorine up to 0*25 grm. The entire operation need not 

 occupy more than two hours and a half. 



In conclusion the author gratefully acknowledges her 

 indebtedness to Professor Gooch for his valuable advice and 

 assistance given during the progress of this work. 



