Wheeler and Pen field — Alkaline Iodates. 129 



Calculated for CsT0 3 . 

 Cfesium, 43'08 43'53 43-18 



Iodine, 40-84 41-23 



Oxygen, 15-74 15-59 



This was also obtained in attempts to prepare a caesium salt 

 corresponding to 3E,bCl . 2HI0 3 by adding caesium hydrate or 

 carbonate in moderately strong aqueous solution to a strong 

 solution of iodine trichloride in excess, when it at once sepa- 

 rated in the form of a white sandy precipitate, which under 

 the microscope was seen to consist of transparent grains of 

 indefinite form. Unless the iodine trichloride is nearly satu- 

 rated with the carbonate, CsCl . C1 3 I or CsCl . CU* is obtained 

 mixed with the iodate. An iodine and oxygen determination 

 in the air-dried salt gave 40*55 and 40-83 per cent of iodine 

 and 15*67 per cent of oxygen. "When this iodate is heated it 

 does not give off iodine but melts and evolves oxygen. The 

 residue is caesium iodide. 



20sIO s . 1JJ V — This substance can be prepared in pure con- 

 dition and in large quantity by mixing a moderately dilute 

 aqueous solution of two molecules of caesium chloride with one 

 molecule of iodine pentoxide dissolved in a little water. Any 

 precipitate that may have been produced is dissolved by the 

 aid of heat and more water if necessary. On cooling, the com- 

 pound separates as a sandy powder. This can be washed with 

 water or recrystallized from hot water without decomposition. 

 It can also be recrystallized from dilute solutions of iodic acid. 

 At 21° 100 parts of water dissolve 2*5 parts of this salt. It is 

 insoluble in alcohol. The material for analysis was air-dried 

 after pressing on paper. 





Found. 



Calculated for 2CsIO s 



.I 2 



Caesium, 



27*93 



28*00 





Iodine, 



53*42 



53-47 





Oxygen, 



18-69 



18-53 





This compound invariably separates along with the crystals 

 of CsCl . C1 3 I, when the latter is prepared in the absence of 

 hydrochloric acid. The yield is not very large. It is thus 

 obtained in the form of small rounded white nodules which on 

 close inspection are seen to occur in pairs, the two nodules 

 being on opposite sides of a thin layer of the pentahalide. 

 They were mechanically separated from the pentahalide, no 

 water being used to wash the compound when prepared for 

 analysis. The following results are sufficient for its identifica- 

 tion. 



*This Journal, III, xli'i, 17, and xlir, 42. 



