460 POTASSIUM. 



the nitre from 1 parts of ordinary gunpowder, with water, and 

 mixing the residue intimately, while still hurnid, with 5^ parts 

 of chlorate of potash in an extremely fine powder. This mix- 

 ture is highly inflammable when dry, and dangerous to preserve 

 in that state. 



Hyperchlorate of potash; KO, C1O 7 ; 173<2.6 or 138.83. 

 Processes for preparing this salt have already been described 

 under hyperchloric acid (page 370). It is also formed in a 

 strong solution of chlorate of potash contained in the decom- 

 posing cell of a voltaic battery, this salt being deposited in small 

 crystals upon the zincoid, and no oxygen liberated there. It 

 requires 55 parts of water to dissolve it at 59, but is largely 

 soluble in boiling water. It crystallizes in octohedrons with a 

 square base, which are generally small; they are anhydrous. 

 It deflagrates less strongly with combustibles than the chlorate ; 

 loses oxygen at 400, and is completely decomposed at a red 

 heat, chloride of potassium being left. 



lodate of potash ; KO, IO 7 ; 2669.4 or 213.92. This salt 

 may be formed by neutralising the chloride of iodine with car- 

 bonate of potash, instead of carbonate of soda (page 390). It 

 gives small anhydrous crystals which fuse by heat, and lose all 

 their oxygen. lodic acid likewise forms a biniodate and a terio- 

 date of potash, according to Serullas*. The biniodate is obtained 

 by adding an additional proportion of iodic acid to a solution of 

 neutral iodate saturated at a high temperature ; it contains an 

 equivalent of water, but may be made anhydrous by a strong 

 heat, according to my own observations. It occurs in prisms 

 with dihedral summits, and requires 75 parts of water at 59 to 

 dissolve it. The teriodate is obtained on mixing a strong acid, 

 such as nitric, hydrochloric, or sulphuric, with a hot saturated 

 solution of the neutral iodate, and allowing it to cool slowly. 

 It crystallizes in rhombohedrons, and requires 25 parts of water 

 to dissolve it. 



Serullas has observed that the biniodate of potash has a great 

 disposition to form double salts. A compound with chloride 

 of potassium,, to which he assigned the formula K Cl + KO, 

 I. 2 O 10 , is obtained on adding a little hydrochloric acid to a solu- 

 tion of iodate of potash, and allowing the solution to evaporate 

 spontaneously. This salt crystallizes well, but afterwards loses 



* Ann. de Ch. et de Phys. t. 43. 



