44 On the Identity of the Pjromucous, 



matic nature, which gave them a ftriking refemblance, when 

 chemifts wiihed to explain what were the peculiarities of 

 each fpecies, they were obliged to acknowledge that the exa- 

 mination of thefe productions of fire had not been carried to 

 a fufficient length, and that their properties had not been fo 

 thoroughly Studied as to enable them to aflign characters 

 Sufficiently ftriking, and to give a correct hiftory of them. 



V. Firjl View of the Acetous Nature of the "Empjyreumatic 



Acids. 



Such was the uncertain ftate of the Science in regard to the 

 three acids extracted from vegetable matters by fire, when a 

 circumstance, prefented, as it were, accidentally, gave us an 

 opportunity of discovering a new fact respecting their nature. 

 In the courfe of thofe refearches in which C. Vauquelin and 

 my Self* have been fo long engaged respecting the chemical 

 analyfis of vegetable Substances, and of the experiments 

 which wc made on the Solid or ligneous parts of plants, we 

 were employed Some months in the examination of cork. 

 This epidermal covering of a fpecies of oak had appeared to 

 jne, for feveral years, to be of a nature fo very diftinct from 

 other vegetable tiffues as to deferve a particular refearch : 

 feveral experiments on the epidermis of other trees had in- 

 clined me to think t;hat in their characters they approached 

 near to cork, and I thought it mv duty to prefent it as one 

 of the immediate material* of plants under the name of 

 fuber. Being defirous of carrying my firft eflays ftill further, 

 and of giving more extent to ihcle firft ideas, we began to 

 employ ourfelves this Summer on a more exact analvfis of 

 cork. Having Subjected a pretty large quantity of it, cr6ilb. 

 (three hectogrammes), to distillation with a naked lire, we. 

 obtained from it a fourth of its weight of a very light and vo- 

 latile oil, and almoft the fume quantity of a reddifti empyreu- 

 inatic liquid, which exhibited all the apparent characters of 

 the pyro'igneous acid. But this acid liquor, when examined 

 with more care, rectified and combined with alkalies, and 

 difengage4 from its bafes by weak fulphuric acid, foon exhi- 

 bited properties of real acetous acid, and, after having Sepa- 

 rated it by flew diltillation from the portion of coloured oil, 



w hich, 



