IODIDES. 393 



When caustic soda is added to the solution of iodine in alco- 

 hol or wood-spirit, a yellow substance of a saffron odour preci- 

 pitates, which was supposed by Mitscherlich to be the period ide 

 of carbon, but is iodoform, of which the formula is C 2 H I 3 . 

 No true iodide of carbon is known. 



Iodide of sulphur. This compound is formed by fusing to- 

 gether 4 parts of iodine and 1 of sulphur. It has a radiated 

 crystalline structure, but its elements are easily disunited, the 

 iodine escaping entirely from this compound when it is left ex- 

 posed in the air. 



Iodides of phosphorus. Iodine appears to combine with 

 phosphorus in several proportions, when they are brought in 

 contact and slightly heated. In all these combinations, the mass 

 becomes hot without inflaming, if the phosphorus is not at the 

 same time in contact with air. One part of phosphorus with 

 6, 12 and 20 parts of iodine forms fusible solids, which may 

 be sublimed without change, but which are decomposed by 

 water, all of them yielding hydriodic acid, and the first 

 affording besides phosphorus and phosphorous acid, the second 

 phosphorous acid, and the third phosphoric acid. 



Chlorides of iodine. Chlorine is readily absorbed by dry iodine 

 and perhaps more than one compound formed. Berzelius forms 

 a definite compound by distilling a mixture of 1 part of iodine 

 with 4 parts or more of chlorate of potash. There is formed in 

 the retort, a mixture of iodate and hyperchlorate of potash, 

 at the same time that oxygen gas is disengaged, and a chloride 

 of iodine is formed which condenses in the receiver. This chlo- 

 ride of iodine is a yellow or reddish liquid, of an oily consistency, 

 of a sharp and peculiar odour, and of a taste which is feebly 

 acid, but very astringent and rough. It is soluble in water and 

 alcohol ; and ether extracts it from its aqueous solution unaltered, 

 so that it is not decomposed by solution in water. It is sup- 

 posed to consist of single equivalents of chlorine and iodine.* 



When iodine is completely saturated with chlorine, it forms 

 a compound which is solid and yellow, fusible by heat, but 

 which cannot be sublimed without loss of chlorine. It fumes 

 in air and has an acrid odour. It is decomposed by water and 

 forms a colourless solution, which consists of hydrochloric and 

 iodic acids. This proves the composition of this iodide to be 



* Berzelius, Trait de Chimie, 1. 1, p. 110. 



