Chemistry, 181 



The bromates are analogous to the chlorates and iodates. Thus the bro- 

 mate of potassa is converted by heat into the brorauret of potassium, with 

 disengagement of pure oxygen, deflagrates when thrown on burning char- 

 coal, and forms with sulphur a mixture which detonates by percussion. 

 The acid of the bromates is decomposed by deoxidizing agents, such as the 

 sulphurous acid and sulphuretted hydrogen, in the same manner as the acid 

 of the iodates. The bromates likewise suffer decomposition from the ac- 

 tion of hydro- bromic and muriatic acids. 



The bromate of potassa does not precipitate the salts of lead ; but occa- 

 sions a white precipitate with the nitrate of silver, and a yellowish-white 

 with the proto-nitrate of mercury ; — characters which, if correctly observed, 

 distinguish the bromate from the iodate and chlorate of potassa in a very 

 satisfactory manner. 



The bromic acid may be procured in a separate state by decomposing a 

 dilute solution of the bromate of baryta with sulphuric acid. From the 

 analysis of the bromate of potassa, it appears to consist of one atom of 

 brome and five atoms of oxygen, and is consequently similar in constitu- 

 tion to the iodic, chloric, and nitric acids. 



Brome unites with chlorine at common temperatures, forming a very 

 volatile liquid of a reddish-yellow colour, penetrating odour, and exceed- 

 ingly disagreeable taste. It is soluble in water, and dissolves in that li- 

 quid apparently without decomposition ; for the solution bleaches litmus 

 paper without previously reddening it, and has the characteristic odour 

 and colour of the compound. By the action of alkalies it is resolved into 

 muriatic and bromic acids. M. Balard has also described compounds of 

 brome with iodine, phosphorus, and sulphur. With olefiant gas it pro- 

 duces an oily fluid, denser than water, and of a mild ethereal odour. This 

 substance, when transmitted through a red hot tube, suffers decomposi- 

 tion, charcoal being deposited, and hydro-bromic acid gas evolved. It 

 is therefore very analogous to the hydro-caiburet of chlorine. 



Brome exists in sea water in the form of hydro-bromic acid, combined, 

 in the opinion of M. Balard, with magnesia. It is present, however, in very 

 small quantity ; and even the uncrystallizable residue called bittern, left 

 after the muriate of soda has been separated from sea water by evaporation, 

 contains but little of it. On adding chlorine to this liquid, an orange- 

 yellow tint appears ; and on heating the solution to the boiling point, the 

 red vapours of brome are expelled, which may be condensed by a freezing 

 mixture. A better process for preparing brome is to transmit a current 

 of chlorine gas through the bittern, and then to agitate a portion of ether 

 with the liquid. The ether dissolves the whole of the brome, from 

 which it receives a beautiful hyacinth red tint, and, on standing, rises to 

 the surface. When the ethereal solution is agitated with caustic potash, 

 its colour entirely disappears, and, on evaporation, cubic crystals of the 

 hydro-bromate of potash are deposited. 



M. Balard has ascertained that brome exists in marine plants which 

 grow on the shores of the Mediterranean Sea, and has procured it in ap- 

 preciable quantity from the ashes of the sea-weeds that furnish iodine. 



