■Pyrolartareous, and Pyroligneous Afids. 47 



by diftillation, very pure acetous acid, almoft without empy- 

 reumatic odour or fumes. 



' It mull here be obferved that the pyroligneous acid, that 

 of the three acids obtained by fire which has the moft linking 

 empyreumatic odour and character, is alfo one of the three 

 molt difficult to be purified, and to be carried to the ftatc of 

 very pure vinegar. It docs not, therefore, affume the nature* 

 of the lull, as the tartareous acid does, by filtration alone, 

 nor even by two fucceffive di filiations from off powdered 

 charcoal. By employing even the aid of ebullition and 

 ftrong agitation with charcoal, it cannot be deprived of its' 

 oil, while both of thefe precedes fucceed with certainty and 

 eafe in purifying the pyromucous acid, which, indeed, gives 

 up with moll eafe its oil; and even in purifying the pyrotar- 

 tareous acid, though it be a little more difficult to feparate its 

 oil than that of the pyromucous acid. 



But though it is more refraclory in oppofing purification, 

 and that kind of analyfis of which I here fpeak, it is no lefs 

 proved, that the pvroligneous acid, like the two preceding, is 

 only acetous acid impregnated with empyreumatic oil, pro- 

 duced from wood altered by heat. 



VII. Artifrial Convcrjion of the pure Acetous Acid into the 

 Pyromucous, Pyrotartareous, and Pyroligneous Acids. 



The preceding experiments might be fufficient to make us 

 acquainted with the identic and real acetous nature of the 

 three empyreumatic acids, which have been hitherto confi- 

 dcred as forming three diftinct acids, and belouging to a 

 genus well characterifed. But to thefe experiment* a fupple- 

 jnent was If ill wanting; it was necefiary to inquire whether 

 it was not poflible to imitate thefe acids with that of vinegar, 

 by adding what fcemed to be added to it in each of thefe acids 

 produced by lire. 



It was before fully proved that each of thefe produces of 

 diftillation differed hum the other two by an empyreumatic 

 oil united to it by the eifect of its diftillation alone. It was 

 very eafy, therefore, to try to dillil vinegar from off oils dif- 

 tillcd from a mucilage, tartar, and wood. This trial was 

 attended with all the fuccefs that could be expected. Acid 



