508 



A solution of the triple compound, in sulphurous acid, -when dis- 

 tilled, yields iodine, and leaves sulphate of potash ; but the pheno- 

 mena are variously modified, by a greater or less proportion of either 

 ingredient. 



From such experiments as the author has made on the proportional 

 weights of the constituents of this salt, he considers it perfectly ana- 

 logous to hyperoxymuriate of potash ; and its constitution will be re- 

 presented by one of potassium 75, six of oxygen 90, and one of io- 

 dine 165. 



The author also made triple compounds with iodine and alka- 

 line earths, which, like oxyiode of potash, contain a redundance of 

 oxygen, separable by heat, and gave hopes that a compound of iodine 

 and oxygen, similar to euchlorine, might be obtained from some of 

 them ; but these salts are not decomposable by acids ; for even the 

 oxyiode of barytes is not decomposed by sulphuric acid, and hence 

 no compound of iodine and oxygen has yet been obtained in a sepa- 

 rate state. 



From hydriodic gas, or from the acid formed by union of this gas 

 with water, iodine may be obtained by union with oxygen, by nitric 

 acid, by hyperoxymuriate of potash, or even by absorption of oxygen 

 from the atmosphere. 



This acid unites with the alkalies and common earths into com- 

 pounds very analogous to the corresponding compounds with mu- 

 riatic acid, but decomposable, in a certain degree, by heat when 

 oxygen is present, which occasions most of these compounds to be- 

 come alkaline when long heated. 



Although chlorine and iodine unite in all proportions, there is one 

 compound nearly colourless that appears to be definite, having strongly 

 acid properties, and the author terms this chloriodic acid. When any 

 of these compounds are mixed with alkaline solutions, the tendency 

 appears to be, in the first instance, to form oxyiodes with the alkali 

 or earth present ; but the phenomena necessarily vary according to 

 the proportion of the several ingredients present. 



In the next set of experiments, which the author made with gases, 

 the results appear to be regulated by the presence of hydrogen, form- 

 ing hydriodic acid with the iodine, as in the instances of olefiant gas 

 and sulphuretted hydrogen. 



No change was produced in nitrous gas, nor in carbonic oxide, to 

 which iodine was exposed in common day-light, nor even when it was 

 sublimed in it ; but it appeared doubtful whether there might not be 

 some tendency to combine when the violet vapour was formed by 

 heat in full sunshine. 



In conclusion, the author reports various unsuccessful attempts to 

 obtain iodine from different species of sea- weeds, and from sea- water, 

 on the shores of the Mediterranean ; and he recommends silver as a 

 test of its presence, since water containing only T-oVirth part of its 

 weight of any salt of iodine tarnishes polished silver, even after boil- 

 ing with muriatic acid, although this property is destroyed in sul- 

 phurets by similar treatment. 



