Wheeler and Penfield — Alkaline Iodates. 127 



The addition of a saturated solution of rubidium chloride to 

 syrupy iodic acid produces a precipitate which dissolves again 

 in the excess of iodic acid. When more rubidium chloride is 

 added, the whole being kept over a lamp, a point is reached 

 where a precipitate begins to form in the hot solution. This 

 is the compound in question. It was identified by a rubidium 

 and an iodine determination. This gave 14*17 per cent of 

 rubidium and 61'83 per cent of iodine. 



RbCl. S10 3 . — This salt can be made by simply allowing a 

 saturated solution of RbCl . C1 3 I to stand for some hours, when 

 large colorless prisms form, attached to the plates of RbCl . 

 C1 3 I. The solution, after removing the crystals, warming to 

 dissolve the pentahalide and pressing chlorine in again, does 

 not yield a further deposit of the substance. This is explained 

 by the fact that so much hydrochloric acid is formed in the 

 solution that the formation of this compound is prevented. 

 The crystals remain unaltered on exposure to the air. On 

 treatment with cold water they are decomposed, losing their 

 luster and becoming white. The solution has an acid reaction 

 towards litmus. The hot saturated solution of this compound 

 gives the normal iodate on cooling. The material for analysis 

 was mechanically separated from adhering RbCl . C1 3 I and 

 dried in the air. 



HIO3. 





Found. 



Calculated for RbCl 



Rubidium, 



• 28-88 



28-78 



Iodine, 



42-29 42-62 



42-76 



Chlorine, 



12-09 12-13 



11-95 



Oxygen, 



16-33 



16-16 



Hydrogen, 



•26 



•33 



This salt can also be prepared by adding a strong aqueous 

 solution of rubidium hydrate to a strong solution of iodine 

 trichloride in water. This gives at first a precipitate of the 

 compound 3RbCl . 2HI0 3 , and the solution left at rest for a 

 few days gives the large well developed crystals of RbCl . 

 HI0 3 unmixed with RbCl . C1 3 I. These were identified by 

 their crystalline form. 



On warming the crystals with hydrochloric acid RbCl . C1 3 I 

 is formed, probably according to the following equation : 



RbCl.HI0 3 + 5HCl=RbCl.C] 3 I + 3H 2 + Cl„ 



and the RbCl . C1 3 I on further heating gives RbCl . C1I with 

 the liberation of chlorine. When the substance is heated it 

 melts, gives off water, chloride of iodine, and oxj^gen the 

 residue consists of rubidium chloride and iodide. A deter- 

 mination of the halogens in this residue gave 3'52 per cent 

 of chlorine and 53 - 66 per cent of iodine. 



