Difference between the Acetous and Acetic Acids. 52 1 



of the oxyJe of copper in the acetous acid, and when this fait is diftilled, the acetous acid is 

 decarbonated. Part of the carbone combines with the oxygen of the oxyde of copper, and 

 efcapes in the form of carbonic acid ; while the other part remains in its folid form in the 

 retort along with the oxyde itfelf. The acetous acid, thus deprived of a portion of its car- 

 bone, paffcs into the receiver with charafters which no longer appertain to the acetous acid, 

 and the oxyde of copper is nearly reduced to the metallic ftate. 



The acetous does not therefore become acetic acid, but by a fubtra£llon of carbone. It 

 appears that the metallic oxydes alone, and fome of the acids, are capable of elFedting this 

 decompofition. 



The acid appears, therefore, to exift in the ftate of acetous acid in the fait of copper, im- 

 properly called acetite. It does not become acetic acid but by diftillation, becaufe it is by 

 this procefs only that it lofcs a portion of its carbone. 



Independent of the proofs we have exhibited in fupport of this truth, we may adduce the 

 two following fa£i:s : 



I . When verdigreafe is manufactured with the diftilled acetous acid of copper, a pure fait 

 is obtained, which affords by diftillation the fame produils as the cryftals of Venus, or the 

 acetate of copper. I have mentioned this fafl: in a memoir concerning the compound pro- 

 cefles of the fabrication of verdigreafe. 2. Every one knows that vinegar is fo much the 

 ftronger, and more completely approaches in its fmell to the acetic acid, in proportion as it 

 is more completely deprived of the extraftive matter with which it was combined. AVe may, 

 in this cafe, confider the acid of vinegar as originally exifting in a ftate nearly faporaceous, 

 which diminilhes its aftion, and weakens its properties. It is difengaged from this addition, 



1 . by fimple repofe, which fufFers part of the extra£tive matter to precipitate, or fall down ; 



2. by the fulphuric acid, which decompofes and more completely carbonizes the extraftive 

 matter ; 3. by the oxyde of copper, which retains a portion of the fame principle with which 

 it appears to form a pyrophoric combination. 



I was defirous of afcertaining whether the acetic acid could be brought back to the ftate 

 of acetous acid, by caufmg it to refume, in the courfe of diftillation upon carbone, that por- 

 tion which it had loft : but all the methods I made ufe of to fucceed in this refpedl were 

 inefFe6lual. 



From the preceding fads I conclude : i. That there is a difference between the acetous 

 and the acetic acids. 2. That this difference arifes from a fmaller proportion of carbone in 

 the acetic acids, than in the acetous. 3. That the acidis in the acetous ftate in metallic 

 falts. 4. That it does not pafs to the acetic ftate but by decarbonization. 5. That the dif- 

 ference between this acid and fome others, equally fufceptible of modifications by a change 

 in the preparation of their conftituent parts, is, that in this the oxygen does not appear fuf- 

 ceptible of addition, or fubtra£lion ; but its carbone alone undergoes which variation, and ' 

 determines all its changes ; whereas in the other acids the oxygen is the principle which is 

 more particularly fubjed to variation, and occaCons the changes obfervable in their properties. 



SCIENTIFIC 



