]Q^j On lodins. [Feb, 



of iodine at. 62-;-° is 4-94S. It melts at 225", and is volatilized 

 under the common pressure of the atmosphere,, at the temperature 

 of .3'J7° or 35G°. 1 ascertained this last temperature by putting 

 iodine in excess in concentrated sulphuric acid, which has little 

 action on it, and observing at what degree of heat its vapours passed 

 up through the acid, I fixed the boiling point at 34/° and 356°, 

 because these two numbers are tlie result of two experiments made 

 in circumstances a little different from each other.* As iodine, 

 when mixed with water, may be distilled over with tli.it liquid, it 

 was at first concluded that its boiling point was nearly the same with 

 that of water; but this is a mistake. At the temperature of 212°, 

 the vapour of iodine mixes with the vapour of water in considerable 

 quantity, and is carried witli it to the receiver wlicre it condenses. 

 Iodine may even be distilled at a much loner temperature. 'Ihe 

 same thing happens to the essential oils ; though they boil only at 

 about 30y°, yet they may l>e distilled over at 212° v.hen mixed 

 Avith water. Iodine seems to be a non-conductor of electricity. 

 When a small fragment of it is put into the galvanic circuit, the 

 decomposiiion of water immediati^iy stops. 



Jodine is not combustible. It cannot even be combined directly 

 with oxvgen. I consider it as a simple substance, and place it, in 

 consequence of the experiments which 1 have made, between sul- 

 phur and cl'.lorine; because its affinities are stronger than the 

 former and weaker than the latter of these bodies. Like them it 

 forms two acids, one by combining with hydrogen, and another by 

 combining with oxygen ; and inost of its combinations have con- 

 siderable analogy with those formed by these two bodies. The 

 compounds of chlorine, iodine, and sulphur with hydrogen, pos- 

 sessing the properties of acids formed by oxygen, ouglit to be com- 

 prehended in the same class, and under the same acid name. 1h 

 order to distinguish them I propose to prefix to the specific name 

 of the acid, which we consider the generic term, hydro; so that 

 the acid combinations of chlorine, iodine, and sulphur with hydro- 

 gen, shall have the names of hydrochloric acid, hydriodic acid, and 

 hydrosulphuric acid. The acid compounds of oxygen with the 

 same bodies, may receive, according to the principles of the 

 nomenclature adopted, the names of chloric, iodic, sulfhnric acids. 

 The terms chlontreis and indnrets may denote the con)pounds of 

 chlorine and iodine with combustibles or oxides. Thus the oxy- 

 inuriate of lime will be called chloruret of lime. 



On the Combination of Iodine with simple Sulslances, a?id in par- 

 ticular of Hydriodic Acid. 



Iodine combines with most combustibles; but I have only exa- 

 mined a few of these combinations. 



♦ These experiments are somewhat hazardous. Though 1 had put pieces of 

 class into the sulphuric aC'J, the iddine in tlie second expciimtnt uiis ronveiled 

 all at once into vapour and drove out the Lot acid which burnt my rijiht Iwiid and 

 foot severely. 



