and Sub-acid Salts. 
99 
Super-oxalate of Potash. 
Exp. 4. The common super-oxalate of potash is a salt that 
contains alkali sufficient to saturate exactly half of the acid 
present. Hence, if two equal quantities of salt of sorrel be 
taken, and if one of them be exposed to a red heat, the alkali 
which remains will be found exactly to saturate the redundant 
acid of the other portion. 
In addition to the preceding compounds, selected as distinct 
examples of binacid salts, I have observed one remarkable 
instance of a more extended and general prevalence of the 
law under consideration ; for when the circumstances are such 
as to admit the union of a further quantity of oxalic acid with 
potash, I found a proportion, though different, yet analogous 
to the former, regularly to occur. 
§. Qiiadroxalate of Potash. 
In attempting to decompose the preceding super-oxalate by 
means of acids, it appeared that nitric or muriatic acids, are 
capable of taking only half the alkali, and that the salt which 
crystallizes after solution in either of these acids, has accord- 
ingly exactly four times as much acid as would saturate the 
alkali that remains. 
Exp. 5. For the purpose of proving that the constitution of 
this compound has been rightly ascertained, the salt thus 
formed should be purified by a second crystallization in dis- 
tilled water ; after which the alkali of thirty grains must be 
obtained by exposure to a red heat, in order to neutralize the 
redundant acid contained in ten grains of the same salt. The 
quantity of unburned salt contains alkali for one part out of 
O 2 
