1826.] ^j^mtained in Sea Wafer. 417 



<jiftT. 



crystds of ligte^romate of potash, but acicular crystals, which 

 appear to oe oromate of potash. Barytes and lime act in a 

 similar manner, but magnesia does not appear to possess the 

 same property. Analogy leads to the conclusion that these 

 two'^5]^^-di s^!^ are connected with the decomposition of water. 



Th^'decomposition of water which is so readily effected with 

 the assistatice of the alkalies also occurs, but in a less complete 

 manner when brome acts upon it, with the assistance of the 

 sun's rays. An aqueous solution of brome which I had for a 

 long time exposed to the rays of the sun, gave sensible indica- 

 tions of the presence of bromic and hydrobromic acids, the 

 formation of which can scarcely be explained but by supposing 

 that w^ater has been decomposed. 



It appears to me from the facts stated in the last and preced- 

 ing paragraphs, that brome acts less strongly upon the metals 

 than chlorine does, but with more energy than iodine ; the 

 evolution of light and heat which accompanies combination of 

 the former with these bodies, shows that brome has more resem- 

 blance to the action of iodine under similar circumstances. 

 Although tin combines with brome with the disengagement of 

 light, which it does not with chlorine, it is, perhaps, dependant 

 upon the circumstance of the brome being fluid, which allows of 

 the combination of greater masses. 



The iodides are decomposed by brome, and the bromurets by 

 chlorine. Iodine, which decomposes potash and soda very 

 readily at a high temperature, does not so act upon barytes, but 

 combines with it to form an iodide of an oxide; brome, on the 

 contrary, effects the decomposition of this base, and also of 

 lime, but it does not act so efficaciously upon magnesia, while 

 chlMj^n^j exerts its decomposing action upon this oxide. 



dafi bq ! QffJiQ Bromic Acid and its Combinations. 



"^hen brome is shaken with a sufficiently strong solution of 

 potash, there are formed, as I have already mentioned, two very 

 different compounds; the hydrobromate of potash is obtained in 

 solution, and a white crystalline precipitate settles at the bottom 

 of the vessel, which appears to be bromate of potash, for it;;. 

 fuses upon burning coals like nitre, and is converted into bromtifi'^ 

 ret of potassium by heat, giving out oxygen gas. 



Bromate of potash is very slightly soluble in alcohol; it dis-'' 

 solves in considerable quantity in boiling water, from which it 

 separates by cooling in the form of needles grouped together. 

 When it is made to crystallize by evaporation, it is deposited in 

 laminas of a dull aspect ; it is decomposed by heat, deflagrates 

 upon red-hot coals, and when mixed with sulphur, it detonateJiis 

 by percussion. // 



The solution of bromate of potash forms a precipitate in Of^^^ 

 of nitrate of silver; this precipitate is white and pulverulent, 



New Series, vol. xii. 2 e 



