Hi/periodic Acid and Hype) iodates. 387 



of a deep brown colour, but did not dissolve ; afterwards almost 

 black; and they became of a fine red by powdering. On the con- 

 trary, by evaporating the solution of the precipitate in nitric acid, 

 until the salt crystallized in the hot solution, crystals of a yellow 

 orange colour were procured. 



By these processes these three different combinations of hyper - 

 iodic acid and oxide of silver were obtained. They were analysed 

 by heating in a glass retort to obtain the oxygen, and the silver 

 was obtained by solution in nitric acid, and precipitated by the 

 muriatic. 



The yellow salt appeared to be composed of 



Iodine 28-598 



Oxygen 16-307 



Silver 48-981 



Water 6-114- 



100-000 

 Supposing hyperiodic acid to contain 7 atoms of oxygen, it will 

 appear by calculation that this salt is a dihyperiodate of silver con- 

 sisting of One atom of hyperiodic acid. . . . 182 

 Two atoms of oxide of silver ... . 236 

 Three atoms of water 27 



445 

 The red salt appeared'by analysis to differ from the above only in 

 containing but one atom of water, or 



One atom of hyperiodic acid. ... 182 

 Two atoms of oxide of silver . .. . 236 

 One atom of water 9 



427 

 The orange salt consisted of 



One atom of hyperiodic acid .... 182 

 One atom of oxide of silver 118 



300 

 This salt is therefore neutral and anhydrous. It is decomposed 

 by water into a subsalt and hyperiodic acid: this occurs at com- 

 mon temperatures. The form of the crystals is destroyed, a straw- 

 coloured subsalt is deposited, and the liquor, separated by the filter, 

 acts as an acid, and does not contain any silver, but merely hyper- 

 iodic acid dissolved in water. This is the best method of obtaining 

 this acid in a pure state. When the orange salt is treated with 

 hot water, the same effects are produced, except that the remaining 

 subsalt is not the yellow, but the red one. 



Hyperiodic acid, thus obtained, may be heated to ebullition without 

 decomposition : by evaporation, crystals are obtained which do not 

 deliquesce. At a high temperature they lose part of their oxygen 

 and are converted into iodic acid ; at a still greater heat they are de- 

 composed into oxygen and iodine. Muriatic acid converts them into 

 iodic acid, chlorine being evolved. 

 3 D2 



