236 Intelligence and Miscellaneous Articles, 



'b 



same time free chromic acid is developed. If, when all the potash 

 has been converted into chloride of potassium and water, the solu- 

 tion is allowed to cool, it soon deposits large crystals of bichromate 

 of chloride of potassium ; so that all the bichromate of potash is 

 converted into water and bichromate of chloride of potassium be- 

 fore the muriatic acid, supposed to be in excess, produces proto- 

 chloride of chrome, which only happens by the decomposition of 

 the salt which is formed. 



The atomic reaction is thus given : — 



Atoms employed. 



2 atoms chromic acid 1304 



1 atom potash 589 



2 atoms muriatic acid 454? 



2347 



Atoms produced. 

 2 atoms chromic acid. ..... 1304 



1 atom chloride of potassium 931 

 1 atom water 112 



2347 



The principal properties of this salt are, that it crystallizes very 

 easily; the crystals are right prisms with rhombic bases; their co- 

 lour is similar to that of bichromate of potash ; they do not de- 

 liquesce. The action of water on this salt is remarkable : when a 

 crystal is moistened with it, it becomes white and opake; and if 

 the solution be suffered to evaporate spontaneously, no crystals of 

 the salt in question are obtained ; but merely those of bichromate 

 of potash. This latter salt is, indeed, produced whether the liquor 

 be concentrated by heat, or exposed to spontaneous evaporation. 

 It appears, then, that water is decomposed by the bichromate of 

 chloride of potassium: its hydrogen combines with the chlorine to 

 form muriatic acid which becomes free, while its oxygen unites with 

 the potassium. 



This reaction produces precisely the products employed before 

 the formation of the bichromate of the chloride, and the nature of 

 the operation will be shown by transposing the atoms above given : 



Atoms produced. 



2 atoms chromic acid . . 1304 



1 atom potash 589 



2 atoms muriatic acid . . 454 



Atoms employed. 

 2 atoms chromic acid .... 1304 

 1 atom chloride of potassium 931 

 1 atom water 112 



2347 2347 



By the addition of a sufficient quantity of muriatic acid, to cor- 

 rect the oxidizing action of the water, the bichromate of the chlo- 

 ide is reproduced. On account of this action of the water, it is 

 impossible to purify this salt by crystallization : it is requisite to 

 press it between folds of blotting paper : it almost always contains 

 a slight excess of chlorine. 



The most ceconomical process for obtaining this salt has been 

 already stated ; it may also be obtained, and in a more direct man- 

 ner, by mixing 2 atoms of chromic acid with 1 atom of chloride of 

 potassium, provided the solution be rendered acid by muriatic acid. 

 It may be procured also by treating bichloride of chrome with 

 water saturated with chloride of potassium ; and in this case all the 



