40 



For the ordinary estimation of the iodine 200 c.e. of 

 brine were put hit* a separating funnel, and after acidifying; 

 slightly and adding a few drops of "nitrose,'* the free iodine 

 was removed by extracting about six times with small quan- 

 tities (5-10 c.c.) of chloroform. To the combined extracts was 

 added potassium bicarbonate solution, and the iodine titrated 

 with — ythiosulphate. The thiosulphate was standardized 

 against y^potassium iodide. Of this solution 1*51 c.c. were 

 greatly diluted and subjected to the same processes as the 

 brine: — 1 "5 1 c.c. T ^ T) potassium iodide = 1*55 c.c. thiosulphate. 



Also, 200 c.c. brine ( = f gallons water) took 1*45 c.c. 

 thiosulphate = '0018 grm. iodine. 



Whence 1 litre of water contains '0005 grm. iodine, or 

 1 lb. iodine is contained in 202,000 gallons. 



Bromine. — After removal of iodine, the solution left can 

 be used for the estimation of bromides. Portions were 

 evaporated after adding a small quantity of sugar, the residue 

 heated till charred, extracted with water, and the clear 

 filtrate slightly acidified. It was then titrated with chlorine 

 water, approximately —^ strength, The chlorine water was 

 standardized againsty^KBr, approximately equal volumes of 

 chlorine solution being used in assay and standard. The 

 chlorine solution gradually loses in titre, so that it is advisable 

 to standardize it at the time of titrating the assay. Found 

 1 Hi. of bromine in fa) 1A71 gallons, (b) 1,393, mean 1,435; 

 or 1 litre of water contains '07 grm. bromine. 



Seeing that the iodide content of the water is so small r 

 a direct titration of the brine (i.e., without removal of iodides) 

 is permissible. Such an estimation gave 1 lb. bromine in 

 1,539 gallons, or 1 litre of water contains '065 grm. bromine. 



