1826.] cofifainedin Sea Water. ' 38^5^ 



ether, it is but very slightly soluble in sulphuric acid ; olive oil 

 acts slowly upon it ; it does not redden tincture of tournsol, 

 but decolorizes it rapidly, very much like chlorine. Solution 

 of indigo in sulphuric acid is also decolorized by it. 



The great analogy which I had remarked between the action 

 of brome and that of chlorine upon vegetable colours, made me 

 think that it existed also between the causes of these pheno- 

 mena ; and that brome, having affinity for hydrogen, probably 

 took it as chlorine does from organic bodies which are put in 

 contact with it. This was the motive which directed my expe- 

 riments in my researches after a combination of hydrogen with 

 brome. 



I first tried to make them act directly upon each other, but 

 without success. My trials were more fortunate when I put , 

 brome in action with several gaseous compounds of hydrogen. 

 I obtained by this method a colourless gas, strongly apid, which 

 when absorbed by potash reproduced the cubic crystals which 

 I had already obtained, by agitating the alkali with ether con- 

 taining brome, 



I afterwards tried to procure from these crystals the gaseous 

 matter which they seemed to contain. When treated with con- 

 centrated sulphuric acid, they evolved an acid gas which I re- 

 cognised as hydrobromic acid, when I had found that chlo- 

 rine decomposed it, disengaging vapours of brome, and that 

 certain metals, by taking this substance from it left only pure 

 hydrogen. This acid may be prepared by several processes : 



1. 1 exposed during some time hydrogen mixed with the va- 

 pour of brome to the solar rays, without observing any sen- 

 sible combination ; but I found that hydrobromic acid gas was 

 produced, by exposing the mixture to the flame of a taper, or 

 still better, by introducing an ignited iron wire into the receiver 

 which contained it. 



In all these cases, the action is not propagated throughout 

 the whole mass, as occurs with chlorine and hydrogen ; th^ 

 combination is produced only around the hot body which occa- 

 sions it. It probably would not have so happened, if I had 

 been able to collect and measure the vapours of brome, and to 

 have mixed them with determinate proportions of hydrogen. 



2. Hydriodic acid gas, and sulphuretted and phosphuretted 

 hydrogen gases are decomposed by brome, which is changed 

 into hydrobromic acid, by separating the vapours of iodine, 

 sulphury and phosphorus ; this decomposition is always efiected 

 with the disengagement of heat. 



The volume of gas does not sensibly alter when hydriodic 

 acid gas is decomposed by brome ; and it increases, when the 

 decomposition of sulphuretted and phosphuretted hydrogen is 

 effected by it. Brome acts in the same way upon these com- 



New Series, vol. xii. 2 g 



