Chemical Science. 477 



Cyanide of Bromine. — ^Two parts of dry cyanuret of mercury 

 are to be placed in a tubulated retort, or at the bottom of a long" 

 tube, and being well cooled in a refrigerating mixture, one part of 

 bromine is to be added ; powerful action ensues, with much deve- 

 lopment of heat, and a bromide of mercury with a cyanide of 

 bromine are formed: the latter crystallizes in long needles about 

 the middle of the tube, the small quantity of vapour of bromine 

 gradually disappearing. A small receiver being then attached to 

 the tube, and well cooled, the cyanide is to be sublimed into it, and 

 will form small colourless, transparent crystals, sometimes acicular, 

 sometimes cubical. This substance is very volatile, and has a 

 penetrating odour ; it becomes vapour at 60° Fahr., and crystallises 

 suddenly by cooling. It is soluble in alcohol and water. Caustic 

 alkalies produce a hydro-cyanate and a hydro-bromate. 



The cyanide of bromine is excessively deleterious ; a grain dis- 

 solved in water, and introduced into the oesophagus of a rabbit 

 caused death as instantly as prussic acid would have done. All 

 attempts to decompose bromine by acting upon it in this compound 

 failed. — Annates de Chimie, xxxiv. 95. 



8. On Oxide of Iodine and lodous Acid, by Signor Sementini. — 

 When Sementini first obtained iodous acid *, it was by heating a 

 mixture of equal parts of iodine and chlorate of potash ; but the 

 latter salt not being pure, variable results were obtained. He then 

 mixed iodine with chlorate of potash in a mortar, adding the 

 former until a clear yellow colour was produced. Upon heating 

 this mixture, yellow vapours appeared at first, which condensing on 

 the neck of the retort used, did not redden the tincture of litmus ; 

 but continuing the operation, a dense oleaginous fluid was obtained, 

 reddening litmus, which, exposed to air, first absorbed a little mois- 

 ture, and then was volatilized ; having a very pungent, unpleasant 

 and slightly acrid taste, and being decomposed by phosphorus, 

 sodium, and potassium at common temperature, with the evolution 

 of vapours of iodine. 



In the operation referred to, it appeared that the first portion of 

 iodine and oxygen combined to form a new compound oxide of 

 iodine ; that afterwards the action of the heat caused the combina- 

 tion of a larger proportion of oxygen with the iodine, and pro- 

 duced two new compounds, — the iodous acid, which, being volatile 

 at a moderate temperature, was condensed in the neck of the re- 

 tort ; and iodic acid, which remained combined with the potash of 

 the chlorate decomposed ; a small portion of chlorine being at the 

 same time set free, and rendering the last portions of iodous acid 

 impure by its presence. 



in consequence of these actions, the following method of pre- 

 paring iodous acid is preferable to that first published, as supplying 



* Quarterly Journal of Scienge^ vol. xvii, p. 381. 



