273 On Super-acid and Sub- acid Salts. 



quantity of sulphuric acid which remains in the vessel in i 

 gaseous slate at a red heat. 



In the preceding experiments, the acids are made to as- 

 sume a determinate proportion to their b.ise, bv heat which 

 cannot desiroy them. In those which follow, the propor- 

 tion which a destructible acid shall assume cannot be regu- 

 lated by the same means ; but the constitution of its com- 

 pounds previously fornied, may nevertheless be proved with 

 equal facility. 



Super-oxalate of Potash. 



Experiment Wf . The common super-oxalate of potash is 

 a salt that contains alkali sufficient to saturate exactly half of 

 the acid presetit. 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 satura.t€ 

 the redundant acid of the other portion. 



In addition to the preceding compounds, selected as di- 

 stinct examples of binacid salts, I have observed one re- 

 markable instance of a more extended and general prevalence 

 of the law under consideration ; for when the circumstances 

 arc such as to admit the union of a further quantity of ox- 

 alic acid with potash. I found a proportion, though difTe' 

 rent, yet analogous to the formerj regularly to occur. 



§. Quadroxalate 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 

 accordinffly exactly four times as much acid as would sa,tu- 

 rate the alkali that remains. 



Experiment v. For the purpose of proving that the con- 

 stitution of this compound has been rightly ascertained, the 

 salt thus formed should be purified by a second crystalliza- 

 tion in distilled water; after which the alkali of thirty grains 

 must be obtained by exposure to a red heat, in order to neu- 

 tralize the r.edimdant acid contained in ten grains of the 

 same salt. The quantity of unburned salt contains alkali 

 for one part out of four of the acid present, and it requires 



the 



