CHEMICAL NOTES. 



333 



CHEMICAL NOTES. 



BY H. CROFT, 



PEOBHSSOE OF CHEMISTET IS UNIVEESITT COLLEGE, TOEONTO. 



On the Iodide of Barium. 



Some years since the writer described the crystallised Iodide of 

 Barium, and gave the formula, Ba I + 7 H 0. G. Werther has 

 since examined a similar salt, but gives the formula, Ba I + 2 H 0, 

 corresponding to the formulas of the bromide and chloride. He also 

 describes the crystalline form as idential with that of the bromide, 

 and states that the salt is deliquescent, and becomes reddish-brown 

 in the air, instantaneously. He prepared the salt by acting on hypo- 

 sulphite of barium with iodine, and filtering off from the tetrathionate 

 of barium. 



The writer prepared the iodide, for the former examination, by 

 acting on baryta with iodine ; but recently, by using sulphide of 

 barium with iodine, and by Liebig's process with phosphorus. In 

 each case the salt crystallised in long clear six-sided prisms, with 

 flat terminal planes, no other faces could be detected. The crystals 

 were not deliquescent in a dry atmosphere, on the contrary, they 

 effloresced. No change of colour took place by some days exposure, 

 farther than that they became opaque. By a strong heat iodine is 

 evolved; but 23.61 per cent, of water can be driven out at 160® c. 



The following analyses show the composition of the salt : in I. 

 the water was determined by heating over a lamp, and is too high 

 from loss of iodine ; II. was formed from sulphide of barium ; III. 

 by means of phosphorus ; and IV. is "Werther's analysis, the water 

 being calculated from the loss. 



In an attempt to form the salt by Werther's process, a small 

 quantity was obtained, crystallising in the same form as the above. 



