Answer:
The preparation of alcohol (spirit of wine, vinic alcohol, ethanol, ethyl alcohol) by fermentation dates to antiquity. Closely related to alcohol -- both through history and chemistry -- is ether (ethyl ether, diethyl ether) a compound obtained from alcohol by the action of oil of vitriol (sulfuric acid). When we use the term ether today, we mean specifically diethyl ether or perhaps the generic class of compounds of which it is a member. In the early part of the 19th century, the term "ether" was applied to any volatile including muriatic ether (ethyl chloride) and acetic ether (ethyl acetate).
Raymond Lully (Raimondus Lullius), a Spaniard born in Majorca circa 1235, after a rather dissolute youth, wrote extensively on Christianity and strove to convert the Muslim Moors. The Moors, who brought alchemy to Spain, had an influence on Lully. He described the action of oil of vitriol on spirit of wine to produce oleum vitrioli dulce verum (true, sweet oil of vitriol; ether) in 1275. A description of the preparation of ether by Valerius Cordus, a German botanist/apothecary, was provided in 1561 by the editor of his works, Conrad Gesner.
Fourcroy suggested that ether was formed by the removal of water from ethanol, which Saussere (1807) and Gay-Lussac (1815) confirmed. Boullay discovered that a small amount of sulfuric acid could produce large amounts of ether and water via a continuous process. This observation indicated that sulfuric acid was not functioning as a [stoichiometric] dehydrating agent but rather, as suggested by Mitscherlich and Berzelius, as a catalyst. Neither of them recognized the formation of sulfovinic acid (ethyl hydrogen sulfate). Frobenius observed that the residue from the preparation could form more ether when charged with alcohol; he also gave ether its name, spiritus vini aethereus.
At this juncture it was clear that ether and water were formed by the action of sub-stoichiometric amounts of sulfuric acid and that sulfovinic acid was formed as an intermediate in the reaction. At the time there was no concept of valence or bonds, but rather one of affinity. Electrochemical Theory or Dualism, which held that atoms that were electronegative were attracted to atoms that were electropositive in analogy to the world of inorganic chemistry, had as its chief proponent, Berzelius. Bear in mind that the voltaic pile [Allesandro Volta, (1800)] had been invented and that electrolysis was well-known [Davy (1802), Gay-Lussac (1807)]. If an inorganic substance such as sodium chloride could be formed from electronegative chlorine and electropositive sodium, it followed, so the thinking went, that ethyl chloride, had as its electropositive unit, the radical ethyl.
In 1815, Gay-Lussac had determined that the weight of one volume of alcohol vapor was equal to the weight of one volume of water vapor and one volume of olefiant gas (ethylene), while the vapor density of one volume of ether was equal to the sum of the vapor densities of two volumes of olefiant gas and one volume of of water vapor. Schematically, and in modern terms,
i think pepsin is an enzyme that digests protein (like i think it digests the protein in your stomach or something like that)