154 



ANNUAL REPORT SMITHSONIAN INSTITUTION, 1934 



proposed to obtain it in the pin-e, elemental state by a process some- 

 what similar to that in use on natural brines at their plant in Mid- 

 land, Mich. It was recognized that modifications and refinements 

 would have to be made in the old procedure, but the basic principle 

 was considered practical and economically sound. This process con- 

 sists essentially of (a) oxidizing a natural bromide-containing brine 

 with chlorine to liberate the bromine, (h) blowing the free bromine 

 out of solution with air, and(c) absorbing the bromine from the air 

 with an alkali carbonate solution from which it subsequently can be 

 recovered in a commercially desirable form. 



Through many years of experience and effort, the Dow process has 

 been developed to the point where it is possible to recover, con- 

 sistently, 95 percent of the bromine content of the natural brines. 

 The latter contain approximately 25 percent total solids, consisting 

 chiefly of the chlorides of sodium, calcium, and magnesium, together 

 with approximately 1,300 p. p. m. bromine. Sea water, however, 

 contains about 3.5 percent total solids, and only 65 to 70 p. p. m. 

 bromine. This is approximately the same bromine content as that 

 of the waste effluent from the commercial process just mentioned. 

 Consequently, when laboratory work was started on the problem of 

 removing bromine from sea water, it is not surprising that at first 

 a low efficiency was obtained. 



RESEARCH LABORATORY DEVELOPMENTS 



It was realized that an addition of acid as well as chlorine would 

 be necessary in order to obtain a satisfactory yield of bromine from 

 sea water on account of its alkalinity, as indicated by its pH of 7.2. 



Otherwise, when the solution was chlorinated, 



neutralization would 

 have been effected at the expense of the liberated bromine. At the 

 same time there would have been a corresponding formation of 



