DR. URE ON THE MOIRA BRINE SPRING. 581 



from bromine, from the supposed property of chloride of barium being insoluble, and 

 bromide of barium being soluble, in concentrated alcohol. I have digested in 60 times 

 its weight of alcohol, sp. gr. 0'830, a mixture of chloride and bromide of barium, 

 made by saturating the ethereous stratum with pure water of barytes, evaporating 

 and igniting, and yet I found afterwards that much of the bromide had remained 

 undissolved, evolving its ruddy vapour when acted on by manganese and sulphuric 

 acid. Hence I cannot recommend this process to the analytical chemist. 



Chemical research has two objects ; the discovery of truth, and the improvement 

 of the useful arts. The first object may, in the present instance, be attained with 

 great precision by the followed method. 



Having impregnated the mother liquor with chlorine gas, and agitated the de- 

 hydrogenated fluid with ether, separate the ruddy ethereous stratum by a funnel. 

 More chlorine gas may now be transmitted through the liquor, and more ether may 

 then be agitated with it, when usually a second layer of chloro-bromic ethereous fluid 

 will be obtained, to be added to the former. Saturate exactly the ethereous liquid 

 with a weak solution of pure soda, which may be done with extreme delicacy, in con- 

 sequence of the loss of colour which instantaneously occurs whenever the neutral 

 point is reached. In a few seconds a faint yellow tinge may reappear in the ether, 

 which must be removed by a drop or two of the soda. The colour of bromine is as 

 sensible a test of alkali as litmus. Separate the ether by a funnel, evaporate the sub- 

 jacent saturated solution to dryness, and ignite carefully in a covered platina capsule. 

 Weigh the mixed chlorides and bromides of sodium, and decompose ten grains, or 

 any definite weight, of the mixture by solution of nitrate of silver. From the weight 

 of the silver precipitate the relative proportions of the chloride and bromide present 

 may be determined on the following principles : 



10 grains of chloride of sodium are equivalent to 24*46 of chloride of silver. 

 10 grains of bromide of sodium are equivalent to 18'39 of bromide of silver. 



Hence, if the silver precipitate from 10 grains be altogether a chloride, it will weigh 

 24*46 grains ; and if altogether a bromide, it will weigh only 18*39 grains. The an- 

 nexed Table will show that the differences of weight are sufficiently great for every 

 analytical purpose. 



Chloride of Sodium. Bromide of Sodium. Weight of Silver Precipitate. 



Grains. Grains. 



10 +0 24-46 



9 +1 23-85 



8 +2 23-24 



7 +3 22-64 



6 +4 22-03 



5 +5 21-42 



4 +6 20-82 



3 +7....:. 20-21 



2 +8 19-60 



1 + 9 ...... . 19-00 



+10 18-39 



MDCCCXXXIV. 4 P 



