1815.] Elements of Organic Nahire are eomllned. 101 



Hydrogen 4-218 



Carbon 47-859 



Oxygen 47-923 



100 



The true capacity of saturation of the acid then is 15.9743, 

 instead of 16 given by experiment. 



{To be continued.) 



Article III. 



A Memoir 07i Iodine. By M. Gay-Lussac* 

 (Read to the Frencli Institute on the 1st of August, 1S14.) 



I HAVE already, in tlie sittings of the 6th and 20th of De- 

 cember, 1813, read to the Class the result of my researches + on 

 the substance discovered by M. Courtois, to which I proposed to 

 give the name of iode, on account of the beautiful violet colour 

 of its vapour. To these researches, the object of which was to 

 determine the nature of iodine, and the situation in whicii it ought 

 to be placed with respect to other bodies, I have added new experi- 

 ments, which I have now the honour to communicate to the 

 Class. If there be no occasion to apologize for the length of time 

 which has elapsed since I read my first experiments, 1 must at least 

 beg your indulgence for the details into which 1 am about to enter. 

 I regret that my labours have lost part of their interest, by appear- 

 ing after those of M. Vauquelin, with which 1 was unaccquainted 

 when I drew up ray memoir. But it will be at least a satisfaction to 

 me, if, in the subjects which we have treated in common, 1 have 

 in general drawn the same conclusions as he has done. 



Properties of Iodine. 



Iodine when in a solid state is greyish black ; but its vapour has a 

 fine violet colour. Its odour is exactly that of chlorine, weakened. 

 It is often in scales similar to those of micaceous iron ore, some- 

 times in rhomboidal plates, very large and very brilliant. I have 

 obtained it in elongated octohedrons about a centimetre in length. 

 Its fracture is lamcllatcd, and it has a fatty lustre. It is very soft 

 and friable, and may be rubbed to a fine powder. Its tasle is very 

 acrid, though it be but very little soluble in water. It gives a deep 

 brown stain to the skin, but this colour is soon removed. Like 

 chlorine it destroys vegetable colours ; but with nnieh less energy. 

 Water dissolves about one seven thousandth part of its weight of 

 iodine, and acquires an orange yellow colour. The specific gravity 



« T r.insUipH from (lie AiinnN Hr- Cliimir, vot. \ci. p. 5 July 181 J. 

 [ I'r iiiUdiii llif ytiiuuh uj' X'MvSoiihj.^ iii. 100. 



