Chemical Science. 175 



When chlorine was passed over this iodide in powder at common 

 temperatures, it was absorbed, rendering the yellow iodide white ; by 

 applying a slight heat, the iodine was driven off, and the chloride 

 of silver left; but as this substance absorbs chlorine when cold, in 

 small quantities, air was passed through the tube whilst the com- 

 pound was in fusion, until all smell of chlorine had ceased. Five 

 grammes of iodide of silver, decomposed by chlorine, gave 3.062 of 

 chloride of silver; in a second experiment 12.212 of iodide be- 

 came 7.4755 of chloride. Adopting the latter result, the number, 

 according to Berzelius's series, is for iodine 789.145, 8.7011 for the 

 density of its vapour, and 4.4193 for the density of hydriodic 

 acid gas. 



Berzelius makes the number for bromine greater than that given 

 by Balard and Liebeg. To free the bromine from chlorine, it was 

 first washed with much water, then part was changed into salt by 

 ammonia, and the other part by zinc ; in both cases the solutions 

 were first purified by precipitation, with a little dilute nitrate of 

 silver, and afterwards with more for the preparation of the pure 

 bromide ; the first precipitate was much paler than the second, 

 shewing the presence and separation of the chlorine. The latter, 

 after being fused, was a transparent yellow mass, and was decom- 

 posed with more difficulty by chlorine than the iodide. In each ex- 

 periment, the chlorine was passed for three-quarters of an hour after 

 red fumes had ceased to appear. 



It is not said what weight of bromide gave a certain weight of 

 chloride of silver, but only that the mean of two experiments gave 

 489.15 (Berzelius's numbers) for the atomic weight of bromine. 

 The density of the vapour of bromine is said consequently to be 

 5.3933, and that of hydrobromic acid 2.731. — Annalen der Physik, 

 1828. Ann. de Chimie. 



7. Chloride and Iodide of Nitrogen. — M. Serullas has stated to the 

 Academy of Sciences of Paris, that the detonating substances 

 usually considered as binary compounds of chlorine and iodine 

 with nitrogen, contain also hydrogen, or, in fact, that they are the 

 chloride and iodide of azote. The experiments proving this asser- 

 tion are to be given hereafter. — Le Globe. 



8. Action of Iron on Ammonia. — M. Despretz announced some 

 time since, that when heated metals were subjected to the action of 

 ammoniacal gas, they underwent a considerable change in their 

 weight, in consequence of combining with some part of the ammonia. 

 He now states that the weight of iron is sometimes increased as much 

 as 11.5 per cent, in such an experiment, inconsequence of the com- 

 bination of nitrogen with it. If the temperature applied be too 

 high, the nitrogen is expelled, and the compound destroyed. — Le 

 Globe, April 14. 



