580 DR. URE ON THE MOIRA BRINE SPRING. 



Since the bromine is probably the most important ingredient of the Moira saline 

 water, and since it is the one of which the quantity is most difficult to determine, I 

 now proceed to offer some remarks on its elimination. 



As bromine is always associated with chlorine in the waters from which it has been 

 hitherto extracted, the first object of the analyst is to remove the chlorides as far as 

 possible by crystallization. With this view the salts of lime and magnesia, which are 

 usually present, ought to be decomposed at the outset by a due addition of carbo- 

 nate of soda, so that the mother water obtained by evaporation may contain no deli- 

 quescent chlorides, but consist eventually of the chloride and bromide of sodium. 

 By this precaution, also, none of the hydrobromic acid will be dissipated in the first 

 process, as happens when the bromides of calcium and magnesium are present. 



It is stated by Macquer that chloride of sodium is insoluble in alcohol of specific 

 gravity '840. I find, on the contrary, that a less aqueous alcohol, that of specific 

 gravity 0*830, will dissolve at ordinary temperatures one twentieth of its weight of 

 pure chloride of sodium ; and that the same alcohol will dissolve fully five times 

 as much bromide of sodium. On this difference of solubility in alcohol I sought to 

 establish a simple method of separating the chlorides and bromides of sodium in the 

 mother liquor of saline springs. On triturating with alcohol of 0*830 the saline mass 

 obtained by evaporating the said mother liquor to dryness, a solution was obtained of 

 specific gravity 0*985, which contained nearly one fifth its weight of saline matter, 

 consisting chiefly of chloride of sodium. Thus it appears that a small proportion 

 of bromide of sodium present in the alcohol, enables it to dissolve a large proportion 

 of chloride. The separation of these two salts by alcohol is therefore impracticable. 



The process which I eventually adopted for analysis, was to transmit through the 

 mother liquor of the soda salts a current of chlorine gas till it communicated the 

 maximum golden yellow tint, and then to pour in sulphuric ether, and agitate. The 

 well known reddish yellow stratum of ether, combined with bromine and chlorine, 

 soon rises to the surface of the saline solution. If the mother liquor has been sub- 

 mitted in its most concentrated state to the action of chlorine gas, the quantity of 

 ether should be small in proportion to the bulk of the liquor ; for if too much be 

 added, it will hydrogenate the bromine, and cause the whole mass to become imme- 

 diately colourless. If, on the other hand, the mother liquor be too dilute, it will 

 absorb a quantity of chlorine proportional to its volume, whereby much ether will 

 be decomposed. Distilled water made yellow by chlorine gas affords, on agitation 

 with ether, a yellow supernatant stratum, not dissimilar to that produced by a minute 

 portion of bromine treated in a similar way. It is therefore obvious that the reddish 

 yellow ethereous stratum obtained from the mother liquors of bromic waters, is 

 always a combination of chlorine and bromine with ether, in proportions more or 

 less uncertain. 



Desfosses or Berzelius * prescribes barytes as an agent for separating chlorine 



* Berzelius, Traite de Chimie, i. 294. 



