46 Dr, Clark to Professor Mitscherlich 



gauate of soda contains, not manganic acid, but the oxy- 

 manganic. 



3. The oxymanganate of* soda is assumed to contain, not 

 oxymanganic acid, but another acid, composed of manga- 

 nese 4 atoms, and oxygen 15 atoms. 



Here, again, it may be supposed that material difficulties 

 may be avoided by retaining, without alteration, the first 

 formula for the oxymanganate of soda : — 



So (Mn Sln)2 



But this would involve us in the new inconsistency of as- 

 suming the soda-manganate to have, as a constituent, the 

 same acid as the oxymanganate either of soda or of barytes, 

 while we admit that the barytic-manganate is constituted 

 by a different acid. 



I do not know whether you, or other chemists, may see 

 any way of reconciling with the constitution commonly as- 

 signed to the oxygen-salts, the notion that sulphate of soda 

 and oxymanganate of barytes are analogous in constitution. 

 I profess I can see none. The difficulties already pointed 

 out, as consequences of admitting that analogy, have oc- 

 curred while our attention was limited to those two, and four 

 or live other salts ; but how would such difficulties be mul- 

 tiplied and aggravated, were we resolutely to trace the con- 

 sequences of that admission, throughout all the wide and 

 varied field of chemical combination 1 Wherefore, all idea 

 of analogy of constitution between the two salts in ques- 

 tion, I would renounce as chimerical, did I not believe that 

 such analogy is quite reconcilable with the constitution of 

 oxygen-salts and oxygen-acids, according to the other and 

 better view. I say better view, and I will give reasons ; but, 

 wishing to be brief, I will confine my observations to what 

 may be called internal evidence, arising from a consideration 

 of the constitution of the oxygen-salts, according to both 

 views, as modified by the known results of analysis. 



A being employed to represent an atom of any metal that 

 may be conceived to be in the basis of any oxygen-salt, the 

 following formulas will exemplify the constitution of sul- 

 phates, assumed to contain bases oxidized in different de- 

 grees, according to the view commonly taken of such 

 salts : — 



