412 M» Balard on a peculiar Substance [Dec. 



of oxygen and heat, it resembles, on the other hand^^j;lj^^jj[p.tjter 

 by the property which it possesses of being altexed, j^o^a|jer);aia 

 extent, by sulphuric acid, and by its property pf ^^ao|,^i^g a|^ 

 excess of brome. ,:.,[,,,; ,,,, . 



The action of brome upon the metals greatly r^^eijnble^ that 

 which chlorine exerts upon the same bodies. Ai>ti«a9Ay and 

 tin burn by contact with brome. Potassium evolves, so much 

 heat and light by uniting with it, and so violent a detpnation 

 •ensues as to break vessels of glass in which the union is effected, 

 ^nd to project the result of the combination to a distance. 



The broraurets, which are formed directly with these bodies, 

 ^nd especially the bromuret of potassium, resemble in their 

 ^appearance and properties those which are obtained when the 

 metallic oxides are treated with hydrobromic acid, either in the 

 dry or moist way, after having evaporated the solutions, or caused 

 'them to crystallize. Their aqueous solutions have all the properties 

 of their respective hydrobromates. These facts render it very 

 probable that metallic bromurets, like chlorides and iodides, are 

 'Converted into hydrobromates by solution in water, and recipro- 

 cally the hydrobomates are changed into bromurets in passing 

 *to the solid state : the study of these two orders of compounds 

 wcannot be separated without inconvenience. 



As I have prepared only a few hydrobromates and bromurets, 

 r ".cannot give their general history. It is sufficient to state 

 tfeav * the hydrobromates will be easily recognized by the property 

 whic h they possess of imparting a yellow colour, and emitting 

 brom e, when made to act upon bodies which attract hydrogen 

 stront Hy. Such are the chloric and nitric acids, and especially 

 chlorii le, which explains the use of this last substance in the 

 separat ion of brome ; as to the bromurets, they are all decom- 

 posed b;y chlorine with the disengagement of brome. ,. [y^^^^ 



Bromuret of Potassium. rwolio! 



I employed several processes for the preparation Otf brpniwr^t 

 of potassium. 1. I obtained it by immersing the metal iu the 

 Tapour of brome ; 2. By decomposing hydrobromic acid by it ; 

 :3. By directly combining this acid with potash, evaporating the 

 solution, and drying the residuum ; 4. The cubic ci^ygtals 

 obtained by saturating the ethereal solution of brome, with 

 potash may be considered either as hydrobroraate of potash, or 

 bromuret of potassium. They always contain small portions of 

 muriate of potash or soda ; in whatever mode the bromuret of 

 potassium is obtained, its properties are always similar, and if 

 It be dissolved in water and recrystallized, it usually assumes a 

 tiibic form, and sometimes that of a long rectangular parallelo- 

 •Wp^edj its taste is sharp; when heated^ it decrepitates and 

 •B^d^goes igneous fusion, without suffering any change; chlo- 

 rine decomposes it at a high temperature, brome is evolved, and 



