106 On Iodine. [Feb. 



and a little sulphureted hydrogen, and exhibits, at the same time, 

 the phenomenon of taking fire. It leaves for residue sulphuret of 

 platinum. It is evident that the phenomenon in this case must be 

 referred to the more intimate combination between tlie sulphur and 

 platinum in the sulphuret, than in the-hydrosulphuret. VVe shall 

 see hereafter tiiat the same phenomenon taiies place with one of the 

 oxides of rhodium, which exhibits the appearance of combustion 

 the instant that a portion of its oxygen is disengaged, and it is 

 reduced to a suboxide. 1 shall mention the circumstance more 

 particularly below. 



{To be continued.) 



Article IV. 



On Iodine, the Violet-coloured Substance mentioned in the last 

 Number of the Annals of' Philosopky. * 



The new substance discovered by M. Courtois, noticed in a pre- 

 ceding Moniteur, has been subjected to examination by M. Gay- 

 Lussac, at the request of his friend M. Clement. We shall state at 

 present the principal results which he obtained. 



The new substance to which the name of iodine (from iu^r^z, 

 violaceus,) may be given, possesses in a high degree the electrical 

 properties of oxygen and oxynuiriatic acid. When it has been 

 purified, by means of potash and distillation, it is infusible at the 

 temperature of boiling water, and possesses nearly the volatility of 

 that liquid. No re-agent discovers in it the smallest trace of mu- 

 riati* acid. 



Iodine combines with almost all the metals; but, as it is solid, it 

 does not appear to disengage so much heat in these combinations as 

 oxymuriatic acid does, though in its general properties it has a 

 great resemblance to this body. To give an idea of its relation to 

 other substances, we shall compare it with that acid, applying to it 

 the two hypotheses that have been devised respecting its nature, and 

 we will add that by combining with hydrogen it forms a particnlar 

 acid, very energetic, capable of assuming the gaseous form, very 

 soluble in water, and bearing the same relation to iodine that 



* This curious paper is translated from the Moniteur for the 12th of December, 

 and appears to liave been drawn up l)y M. Gay-Lussac. It will give the chemical 

 reader a raucli more correct view of tliis extraordinary substance than the very 

 impt-rfeci and inaccurate notice in our last Number. A paper by Sir H. Davy on 

 the samp substance has been sput to Sir Joseph Banks. He enters into the requisite 

 details rejpectin; i:* preparation and properties. As soen as it is read before the 

 Royal Society it will make us better acquainted with this new supporter of com- 

 bustion. These supporteis are uow three; and supposing Davy's fluorine to exist, 

 they amount to four. How much these new discoveries must alter the presently 

 received chemical theory, and how tliey serve to con6rm Davy's opiuions respecting 

 nuriutic acid, is too obvious to escape observatioD. — T, 



