CHLORATE OF POTASH. 459 



which are purified by solution and a second crystallization, and 

 more of the same salt is obtained from the liquid evaporated 

 and set aside to crystallize ; the separation of the chlorate from 

 chloride of potassium depending upon the solubility at a low 

 temperature of the former salt being greatly less than that of 

 the latter. When chlorate of potash is prepared upon a still 

 smaller scale, caustic potash may be substituted in the preced- 

 ing process for carbonate. The solution, concentrated by heat, 

 affords crystals of chlorate of potash upon cooling. 



Chloride of lime, after it has lost the greater part of its 

 bleaching power by keeping, a condition in which it is occa- 

 sionally met with in commerce, contains chlorate of lime, and is 

 available in the preparation of chlorate of potash. The solution 

 of the lime salt is boiled for some time, to complete its change 

 into chlorate and chloride ; and then is partially decomposed by 

 means of carbonate of potash, or evaporated with an admixture 

 of chloride of potassium, when chlorate of potash crystallizes 

 out, and chloride of calcium remains in solution (Lowig.) 



This salt is anhydrous. It appears in flat crystals, of a 

 pearly lustre, of which the forms, according to Brooke, belong to 

 the oblique prismatic system. Its density is 1.989 (Hassen- 

 fratz). It has a cooling disagreeable taste, like that of nitre. 

 According to Gay-Lussac, 100 parts of water dissolve 3J parts 

 of chlorate of potash at 32, 6 at 59, 12 at 95, 19 at 120.2, 

 and 60 at 219. 2, the point of ebullition of a saturated solution. 

 This salt fuses readily in a glass retort or tube, enters into ebul- 

 lition, and discharges oxygen below a red heat. At a certain 

 period in the decomposition, when the mass becomes thick, a 

 quantity of hyperchlorate of potash is formed, but ultimately 

 chloride of potassium is the sole residue. 



Chlorate of potash deflagrates with combustibles more vio- 

 lently than the nitrate. A grain or two of it rubbed in a warm 

 mortar, with an equal quantity of sulphur, occasions smart 

 explosions, with the formation of sulphurous acid gas. Inclosed 

 with a little phosphorus, in paper, and struck by a hammer, it 

 produces a powerful explosion ; but this experiment may be at- 

 tended with danger to the operator from the projection of the 

 flaming phosphorus. A mixture which, when dry, inflames 

 by percussion, and which is applied to lucifer matches, is com- 

 posed of this salt, sulphur and charcoal. One of the sim- 

 plest receipts for this percussion powder consists in washing out 



