50 Dr, Clark to Professor Mitscherlich, 



These undeniable actions appear to me to demand evi- 

 dence, such as neveryet has been adduced, in proof of the 

 usual explanation that, in undergoing mutual decomposi- 

 tion by another neutral salt, every neutral Sulphate divides 

 its own Oxygen so as to leave, with the metal it contained, 

 one-fourth, while transferring, to the new Sulphate pro- 

 duced, the remaining three fourths. 



To avoid becoming unseasonably tedious by insisting on 

 such details, I shall draw them to a close, trusting that 

 enough has been stated to establish, that no Chemist is 

 obliged to reject any view, otherwise well founded, merely 

 because that view is inconsistent with the doctrine of Oxy- 

 gen salts having oxides for their bases, provided he per- 

 ceive that the view in question is not inconsistent with the 

 doctrine of Oxygen salts having metals for their bases. 

 Accordingly, I proceed to show that the suggested analogy 

 of Oxymanganate of Barytes and the waterless Sulphate of 

 Soda, although inconsistent with the former doctrine, is 

 quite consistent with the latter. 



Regarded as Hydrogen acids, the acids of the Salts we 

 have been more particularly considering would be 



Oil of Vitriol, H«§ 



Manganic acid, H^Mn 



Oxymanganic acid, H Mn 



I am not sure that Chemists have taken much notice of 

 the varying proportions of Hydrogen in its acids, so far as 

 that element re-places the metallic bases of neutral salts. 

 But, of the following four Hydrogen acids, the Hydrogen 

 varies, without any doubt, in the first and second, and, with 

 much probability, in the third and fourth — 



I. Hydrochloric Acid, H CI 



II. Sulphuretted Hydrogen, . . . H^ S 



III. Hydro-ferricocyanic Acid,'* . . H^ (Fe Cy^) 



IV. Hydro-ferrosocyanic Acid,t . . H'*(FeCy6) 



Sulphuretted Hydrogen, you will observe, has here, in re- 

 spect of Hydrogen, the same relation to Hydrochloric acid 



• Acid that fonns With Potash the red Prussiate. 

 t Acid that forms with Potash the yellow Prussiate. 



