Chemistrtj. 189 



tion of hydro-bromic and sulphurous acids. The distillation is then con- 

 ducted at a gentle heat, and the volatile parts are collected in a cold reci- 

 pient. On diluting the distilled liquor with water, the ether separates and 

 descends to the bottom ; and if any acid has passed over, it may be re- 

 moved by the addition of a small quantity of potash. 



Hydro-bromic ether is colourless and transparent, very volatile, heavier 

 than water, of a strong and ethereal odour, and pungent taste. It is- so- 

 luble in alcohol, and is precipitated from that fluid by water. It under* 

 goes no change of colour by being kept under water, in which respect, it 

 differs from the hydriodic ether. 



15. Cyanuret of Bromine. — The mode of preparing this compound is 

 analogous to that by which M. Serullas procured the cyanuret of iodine. 

 At the bottom of a small tubulated retort, or a rather long tube, are placed 

 two parts of well-dried cyanuret of mercury, so as to secure an excess of it,, 

 and after cooling the apparatus by cold water or a frigorific mixture,- 

 which last precaution is indispensable in summer, one part of bromine is 

 added. A strong reaction ensues, and so much caloric is disengaged that 

 a considerable portion of the bromine would be dissipated unless the tem- 

 perature had been previously reduced. The new products are the bromu- 

 ret of mercury and the cyanuret of bromine, the latter of which collects in 

 the upper part of the tube in the form of long needles. After allowing 

 any vapour of bromine, which may have risen at the same time, to con- 

 dense and fall down upon the cyanuret of mercury, the cyanuret of bro- 

 mine is expelled by a gentle heat, and is collected in a recipient carefully 

 cooled. 



As thus formed, the cyanuret is crystallized, sometimes in small regular 

 colourless and transparent cubes, and sometimes in long and very slender 

 needles. In its physical properties it is so very similar to the cyanuret 

 of iodine, that they may easily be mistaken for each other, especially 

 when the crystals of the cyanuret of bromine possess the acicular form. 

 They agree closely in odour and volatility, but the cyanuret of bro- 

 mine is even more volatile than the cyanuret of iodine. It is converted in- 

 to vapour at 59° F. and crystallizes suddenly on cooling. Its solubility in 

 water and alcohol is likewise greater than that of the cyanuret of iodine. 

 Caustic potash in solution converts it into the hydro-cyanate and hydro- 

 bromate of potash. This solution gives a precipitate of the cyanuret and 

 bromuret of silver, separable from one another by ammonia, which dis- 

 solves the latter and not the former.* The proportion of each may probably 

 be determined in this way. 



M. Serullas remarks, that all the reagents to which he has subjected the 

 cyanuret of bromine always left the bromine with all its characters, even 

 under circumstances favourable to its decomposition, were it not a simple 

 substance. 



The cyanuret of iodine is highly deleterious. A grain of it dissolved in 

 a little water, and introduced into the oesophagus of a rabbit, proved fatal 



" There is surely some mistake here : the cyanuret of silver is soluble in ammo- 

 nia.-^E. T. 



