A formula for a solution of caustic potash was given in the P.L., 1746, under the title of Lixivium Saponarium. Equal parts of Russian potashes and quicklime were mixed, wetted until the lime was slaked, water afterwards added freely, and after agitation the solution poured off. This was ten years before Black’s classic investigation already referred to. Before Black, and for some time afterwards, there were several theories in explanation of the action of the lime on the potashes. The lime had been tamed, but the potash had become more virulent. One popular suggestion was that the lime had withdrawn a kind of mucilage from the potashes; another that it had the effect of developing the power of the potashes by a mechanical process of comminution. A German chemist named Meyer, who vigorously opposed Black’s conclusions, maintained that the lime contained a certain Acidum Causticum or Acidum Pingue, which potashes extracted from it.
In the P.L., 1788, the process was altered by increasing the proportion of the lime, and the product was described as Aqua Kali Puri. Subsequently the proportion of the lime employed was reduced.
The word “salt” is traced back to the Greek “hals,” the sea, from which was formed the adjective “salos,” fluctuating (like the waves), and subsequently the Latin “sal.” Marine salt was therefore the original salt, and salts in chemistry were substances more or less resembling sea-salt. Generally, the term was limited to solids which had a taste and were soluble in water, but the notion was developed that salt was a constituent of everything, and this salt was extracted, and was liable to get a new name each time. Salt of wormwood, for instance, is one of the names which has survived as a synonym for salt of tartar, or carbonate of potash. Paracelsus insisted that all the metals were composed of salt, sulphur, and mercury, but these substances were idealised in his jargon and corresponded with the body, soul, and spirit, respectively.
Lavoisier was the first chemist who sought to define salts scientifically. He regarded them as a combination of an acid with a basic oxide. But when the true nature of chlorine was discovered it was found that this definition would exclude salt itself. This led to the adoption of the terms “haloid” and “amphide” salts, the former being compounds of two elements (now the combination of chlorine, bromine, iodine, cyanogen, or fluorine with a metal), and the latter being compounds of two oxides. The names were invented by Berzelius. Since then salts have been the subjects of various modern theories, electric and other, but they are always substances in which hydrogen or a metal substituted for it is combined with a radical. In a wide sense the acids are also salts.
Alcohol.
Al-koh’l was an Arabic word indicating the sulphide of antimony so generally used by Eastern women to darken their eyebrows, eyelashes, and the eyes themselves. Similar words are found in other ancient languages. Cohal in Chaldee is related to the Hebrew kakhal used in Ezekiel, xxiii, 40, in the sense of to paint or stain. The primary meaning of alcohol therefore is a stain. Being used especially in reference to the finely levigated sulphide of antimony, the meaning was gradually extended to other impalpable powders, and in alchemical writings the alcohol of Mars, a reduced iron, the alcohol of sulphur, flowers of brimstone, and similar expressions are common. As late as 1773 Baumé, in his “Chymie Experimentale,” gives “powders of the finest tenuity” as the first definition, and “spirit of wine rectified to the utmost degree” as the second explanation of the term alcohol. As certain of the finest powders were obtained by sublimation the transfer of the word to a fluid produced by a similar method is intelligible, and thus came the alcohol of wine, which has supplanted all the other alcohols.
Distillation is a very ancient process. Evidence exists of its use by the Chinese in the most remote period of their history, and possibly they distilled wine. But so far as can be traced spirit was not produced from wine previous to the thirteenth century. Berthelot investigated some alleged early references to it and came to the conclusion indicated. Aristotle alludes to the possibility of rendering sea water potable by vaporising it, and he also notes elsewhere that wine gives off an exhalation which emits a flame. Theophrastus mentions that wine poured on a fire as in libations can produce a flame. Pliny indicates a particular locality which produced a wine of Falerno, which was the only wine that could be inflamed by contact with fire. At Alexandria, in the first century of the Christian era, condensing apparatus was invented, and descriptions of the apparatus used are known, but no allusion to the distillation of wine occurs in any existing reference to the chemistry of that period. Rhazes, who died in A.D. 925, is alleged to have mentioned a spirit distilled from wine, but Berthelot shows that this is a misunderstanding of a passage relating to false or artificial wines.
Water distilled from roses is mentioned by Nicander, about 140 B.C., and the same author employs the term ambix for the pot or apparatus from which this water was obtained. The Arabs adopted this word, and prefixing to it their article, al, made it into alembic. This in English appeared for some centuries in the abbreviated form of limbeck. The Greek ambix was a cup-shaped vessel which was set on or in a fire, as a crucible was used.
Pissaeleum was a peculiar form of distillation practised by the Romans. It was an oil of pitch made by hanging a fleece of wool over a vessel in which pitch was being boiled. The vapour which collected was pressed out and used.
Distilled waters from roses and aromatic herbs figured prominently in the pharmacy of the Arabs, and Geber, perhaps in the eighth century, describes the process, and may have used it for other than pharmaceutical purposes. Avicenna likens the body of man to a still, the stomach being the kettle, the head the cap, and the nostrils the cooling tube from which the distillate drips.