334 M, E. Mitscherlich on 



4. Analysis of HyperMoric Acid, and Hyperchlorate 

 of Potash. 



As the salts of hyperchloric acid promised very important 

 results respecting the connexion between the crystalline 

 form and the composition of substances, I had prepared 

 them long ago in considerable quantity. Hyperchlorate of 

 potash is easily formed, by placing a vessel with sulphuric 

 acid in the open air, and throwing into it, in small quanti- 

 ties at a time, fused chlorate of potash in fine powder, at 

 the same time heating the sulphuric acid slightly. If one 

 part of chlorate of potash be added to one part of sulphuric 

 acid, both are completely decomposed, sulphate of potash, 

 perchloric acid, and chlorous acid being formed. The 

 chlorous acid is extricated either undecomposed or as chlo- 

 rine and oxygen, and there is no danger to him who per- 

 forms the experiment, if he take care not to breathe the 

 gas which is extricated. The hyperchlorate of potash is 

 not very soluble in water, while the bi-sulphate of potash 

 is very soluble ; hence, these salts may easily be separated 

 by crystallization. 



In determining the crystalline shape of the hyperman- 

 ganate of potash, which, at the commencement of my 

 experiments, I considered as an acid manganate of potash, 

 I had convinced myself that it was the same as that of the 

 hyperchlorate of potash. From this I suspected at first 

 that hyperchloric acid contained only six atoms of oxygen. 

 At any rate, it was evident that the experiments of Stadion, 

 in which he found this acid to contain seven atoms of 

 oxygen, would require to be repeated, as this proportion 

 had never been observed in any other compound. This 

 induced me, even before I had analysed the hypermanganate 

 of potash, to investigate the hyperchlorate of potash. 



The hyperchlorate of potash may be freed entirely from 

 mechanical water by heat, particularly if it has previously 

 been pounded. Only a low red heat is required to decom- 

 pose it, but towards the end of the ignition it must be raised 

 slightly. The chloride of potassium is at this temperature 

 very volatile, and is partially carried away in vapour along 

 with the oxygen, and carried with it out when it cools. To 

 prevent this as much as possible, the operation must be 

 conducted very slowly, and a long barometer tube, with a 



