Ether.
The action of sulphuric acid on spirit of wine is alluded to in the works of Raymond Lully in the thirteenth century, and in those attributed to Basil Valentine, by whom the product is described as “an agreeable essence and of good odour.” Valerius Cordus, in 1517, described a liquor which he called Oleum Vitrioli Dulce in his “Chemical Pharmacopœia.” This was intended to represent the Spiritus Vitrioli Antepilepticus Paracelsi. It was prepared by distilling a mixture of equal parts of sulphuric acid and spirit of wine, after this mixture had been digested in hot ashes for two months. Probably the product obtained by Cordus was what came to be called later the sweet oil of wine, and not what we know as sulphuric ether.
The first ether made for medicinal purposes was manufactured in the laboratory directed by Robert Boyle, and it is said that he and Sir Isaac Newton made some experiments with it at the time. A paper describing his ether investigations was published by Newton in the “Philosophical Transactions” for May, 1700. In 1700 a paper on ether was published by Dr. Frobenius in the “Philosophical Transactions,” and in the same publication in 1741 a further paper appeared giving the process by which Frobenius had prepared his “Spiritus Vini Ethereus.” Equal parts of oil of vitriol and highly rectified spirit of wine by weight were distilled until a dense liquid began to pass; the retort was then cooled, half the original weight of spirit was added, and the distillation again renewed. This process was repeated as long as ether was produced. Frobenius had been associated with Ambrose Godfrey in Boyle’s laboratory, and Godfrey had been supplying ether for some years, but he does not seem to have published his process. It was in Frobenius’s first paper, published in 1730, that the name of ether was first proposed for the product, which had been previously known as Aqua Lulliana, Aqua Temperata, Oleum Dulce Paracelsi, and such-like fancy titles. Frobenius, it was understood, was a nom de plume. Ambrose Godfrey Hanckwitz, Boyle’s chemist, sharply criticised Frobenius’s article, said it was a rhapsody in the style of the alchemists, and that the experiments indicated had been already described by Boyle. Godfrey was, in fact, at that time making and selling this interesting substance. In France, the Duke of Orleans, a clever chemist, who was suspected to have had some association with the famous poisonings of his time, and whose laboratory was at the Abbaye Ste. Genevieve, was the first to produce ether in quantities of a pint at a time.
Hoffmann’s “Mineral Anodyne Liquor,” the original of our Spiritus Ætheris Co., was a semi-secret preparation much prescribed by the famous inventor. He said it was composed of the dulcified spirit of vitriol and the aromatic oil which came over after it. But he did not state in what proportion he mixed these, nor the exact process he followed.
The chemical nature of sulphuric ether was long in doubt. Macquer, who considered that ether was alcohol deprived of its aqueous principle, was the most accurate of the early investigators. Scheele held that ether was dephlogisticated alcohol. Pelletier described it as alcohol oxygenised at the expense of the sulphuric acid. De Saussure, Gay-Lussac, and Liebig studied the substance, but it was Dumas and Boullay in 1837, and Williamson in 1854, who cleared up the chemistry of ethers.
Ether is alcohol, two molecules deprived of H2O [alcohol, C2H5O HO; ether, (C2H5)2O]. Distilling spirit of wine and sulphuric acid together, it seemed obvious that the sulphuric acid should possess itself of the H2O, and leave the ether. But on this theory it was not possible to explain the invariable formation of sulphovinic acid (a sulphate of ethyl) in the process, nor the simultaneous distillation of water with the ether. Williamson proved that the acid first combined with the alcohol molecule, setting the water free, and that then an excess of alcohol decomposed the sulphovinic acid thus formed into free sulphuric acid and ether, this circuit proceeding continuously.