Wheeler and Pev field — Alkaline Iodates. 125 



The presence of water in these compounds was determined by 

 directly weighing it in a calcium chloride tube, the substance 

 being ignited in a combustion tube containing a mixture of 

 lead chromate and lead oxide. 



Normal rubidium iodate, RbIO v — This compound was 

 made by adding one molecule of iodine pentoxide in either 

 strong or dilute aqueous solution, to a solution of one mole- 

 cule of rubidium carbonate. If the solutions are strong, the 

 iodate separates as a sandy precipitate, but if they are hot and 

 dilute it separates on cooling in small grains or as a crystalline 

 crust. At 28° 100 parts of water dissolve 2*1 parts of the 

 salt. The compound, after filtering on the pump, washing 

 with a little water and drying on paper, gave the following 

 results on analysis : 



Found. Calculated for RbI0 3 . 

 Rubidium, 32-17 32-82 



Iodine, 48-50 48*75 



Oxygen, 20*59 18-43 



The salt when heated decrepitates strongly, melts, gives off 

 oxygen but no iodine, and the residue is rubidium iodide. 

 Hydrochloric acid readily dissolves it in the cold to a faint 

 yellow-colored solution which increases in color on standing. 

 On warming, chlorine is evolved and the solution turns bright 

 yellow from the formation of iodine trichloride. If boiled 

 with strong hydrochloric acid, KbCl . C1I* is formed which 

 separates on cooling. 



The formation of normal rubidium iodate was also observed : 

 when a hot dilute aqueous solution of iodine trichloride was 

 treated with rubidium carbonate. The compound thus ob- 

 tained gave 48*43 per cent of iodine on analysis. Also by 

 dissolving the acid iodate in a strong hot solution of rubidium 

 chloride and allowing the mixture to crystallize. This was 

 identified by a rubidium determination which gave 32*58 per 

 cent. In general the iodates of rubidium all give this body 

 when they are dissolved in hot water and the solutions left to 

 crystallize. The products obtained in this manner decrepi- 

 tated on heating and did not give off iodine. A rubidium 

 determination in the substance obtained from RbCl . HI0 8 

 gave 32-76 per cent ; from 3RbCl . 2HI0 3 , 32*22 per cent. 



Acid rubidium iodate, RblO % HIO v — This was obtained by 

 mixing warm solutions of one molecule of iodine pentoxide 

 and two molecules of rubidium chloride. The compound 

 generally separates on cooling as a heavy crystalline powder. 

 It is difficultly soluble in cold water. Hot water dissolves it 

 more readily and. on cooling, the normal iodate separates. It 



* This Journal, xliii, 475. 



