178 M. E.Miisckerlich on 



2*21 volumes of azotic gas, 

 2*65 volumes of oxygen. 



4-86 

 Now, let the absorbability of azotic gas by water = x and 

 that of oxygen gas = y. We have from the constitution of 

 the atmosphere, 



^ = 2-21. Hence a: = 2-76. 

 o 



I = 2-65. Hence y = 12-25. 



So that oxygen gas is about 4i times as absorbable by 

 water as azotic gas. But, as two-thirds of this oxygen gas 

 absorbed by water disappear, the absorbability of oxygen 

 gas appears only to be to that of azote as 4*5 to 2*76, or 

 not so much as double. 



Article III. 

 On Manganic and Hypermanganic Acids, on Hypercldoric 

 Acid, and the Salts of these Acids. By E. Mitscherlich.* 



ScHEELE first observed a part of the phenomena, which, as 

 I shall immediately show, are produced by two acids formed 

 from manganese ; and after him chemists of eminence have 

 repeatedly turned their attention to the subject. Chevreul, 

 Chevillot and Edwards, Forchhammer, Fromherz and Un- 

 verdorben, have added more or less interesting facts to 

 those previously known, although they have by no means 

 exhausted the subject. These compounds, however, would 

 unquestionably have been long ago completely investigated, 

 had not the great difficulty of obtaining the pure acid in 

 sufficient quantity rendered their examination almost an 

 impossibility. They are decomposed very easily by a great 

 number of circumstances; their solutions cannot be filtered, 

 nor their crystals laid upon paper, because they are instan- 

 taneously decomposed by organic substances. 



Very distinct crystals, which I obtained of manganate of 

 potash, enabled me to determine their shape, and as it was 

 found to agree in every respect with that of the chromate, 

 seleniate, and sulphate of potash, this circumstance, which 



• PoggendorflTs Ann., xxv., 287. (The publication of this interesting paper 

 is rendered necessary to illustrate that of Dr. Clark, printed in Records, vol. iii. 

 43:3, and vol. iv.43. — Edit.) 



