Vitriolic acid

When A. S. Marggraf tried to prepare alum from alumina and vitriolic acid, he found that unless he added fixed alkali he obtained no crystals (19). In 1777 Lavoisier clearly stated that potash is an essential constituent of alum (18, 20). In analyzing a water containing aluminum sulfate, which the younger Cassini had sent him from Italy, Lavoisier added some potash When he evaporated the solution, he obtained crystals of alum and realized that this was a verification of the results of Marggraf and of Macquer. 

Although the acidic constituent of common salt was already known, the nature of its basic constituent was still a matter of conjecture. Soda, natrum, and borax, wrote du Hamel in 1736, give with vitriolic acid Glauber s salt, with acid of saltpeter, cubic saltpeter [sodium nitrate] and with acid of salt, a kind of sea salt. Does this not permit one to decide as to the base of die sea salt (46). 

Although G. E. Stahl and Caspar Neumann both believed that alum contained lime, J. H. Pott was unable to prepare it from lime and vitriolic acid, but always obtained merely selenite (calcium sulfate) (74). When Stahl leached with water a broken clay tube he had used for distilling spirit of vitriol (sulfuric acid), he obtained crystals of alum (74). Pott, too, prepared alum from clay and sulfuric acid (74). 

If it is wished to obtain the marine acid from sal ammoniac, vitriolic acid is employed, known to have greater power than that of marine acid it removes by its superiority of force, the alkali which was its base or its matrix and takes it for its own, and the marine acid, thus disengaged and free, passes off in distillation. ... 

The vitriols, blue, green, and white, were especially important because it was from them that vitriolic acid was prepared. The natural vitriols, copper, iron, and zinc sulfates respectively, were so named presumably because of the glassy surfaces of their crystals (from the Latin vitreus like glass ). 

Sulphur is composed of an acid and the principle of inflammability combined. Take some vitriolic acid, a little nitre or salt of tartar, toss them all into a crucible, put the matter in fusion with some charcoal. With an acid precipitate the resulting mass, and you will have a true sulphur. 

It is composed of an acid salt and the inflammable principle because the vitriolic acid is either changed into an alkali, or evaporated, or remains in the sulphur. It is not changed into an alkali, since the weight of the alkali is not very different from what it was before it is not evaporated, since it can be obtained from the new compound. Moreover by deflagration it produced a bitter salt formed of an acid and an alkali. It lacks for the formation of the sulphur only the inflam-... 

Inflammable air from the solution of metals in acids had been observed and commented on for at least a hundred years, but only after the attention of chemists had been directed toward gases generally did a systematic study appear. Cavendish obtained the inflammable air by dissolving zinc, iron, and tin in dilute vitriolic acid or in spirit of salt. The same metals also dissolved readily in nitrous (nitric) acid, and in concentrated vitriolic (sulfuric) acid with heat, but the resulting airs were not at all inflammable. He interpreted these reactions as follows ... 

To the chemical reader of that day this evidence was sufficient to confirm the presence of the vitriolic acid in the gypsum. 

To determine the nature of the base, Lavoisier added to a solution of the gypsum some concentrated fixed alkali, drop by drop. Immediately the vitriolic acid left its base to unite with the fixed alkali and form with it vitriolated tartar [potassium sulfate]. The solution became turbid and a white precipitate formed, which when washed proved to be a very pure cal-... 

Experiment has fully evinced that sulphur is no other than the concentrated vitriolic acid combined with a small proportion of the phlogistic or inflammable principle, and to this combination alone, which is always one and the same except for adventitious admixtures, the more judicious chemists have wholly confined the name. ... 

It seems likely from hence that when either of the above mentioned metallic substances (zinc, iron, tin) are dissolved in spirit of salt, or the diluted vitriolic acid, their phlogiston flies off, without having its nature changed by the acid, and forms the inflammable air but that when they are dissolved in the nitrous acid, or united by heat to the vitriolic acid, their phlogiston unites to part of the acid used for their solution, and flies off with it in fumes, the phlogiston losing its inflammable property by the union. ... 

New Nomenclature Combinations of Sulphuric Acid with Old Nomenclature Combinations of Vitriolic Acid with ... 

It is water impregnated with vitriolic acid air that may be converted into ice, whereas water impregnated with fluor acid will not freeze. I had observed that with respect to marine acid air and alkaline air (NH3) that they dissolve ice, and that water impregnated with them is incapable of freezing, at least in such a degrees of cold as I had exposed them to. The same I find, is the case with fluor acid air, but it is not so at all with vitriolic acid air, which, entirely contrary to my expectation,... 

I find to be altogether difficult. But whereas water impregnated with fixed air discharges it when it is converted into ice, water impregnated with vitriolic acid air, and then frozen retains it as strongly as ever. ... 

Synonyms Battery acid, Chamber acid, Contact acid, Dipping acid, Fortifying acid, Hydrogen sulfate, Oil of Vitriol, Tower acid, Vitriolic acid. 

This idea of chemical division seems to imply an association between an air and a substance that is intermediate between mechanically separable and chemically compounded. The idea appears repeatedly in both Watt s hints and in Apparatus , but is not expressed consistently. On occasion Watt uses the term suspension to refer to it. For example, inflammable air produced from iron and vitriolic acid, he states always carries with it, even through water, a large quantity of iron some of which it afterwards deposits, but very probably some part still remains suspended 19 The part of the carried-over iron that remains suspended must have a different relationship with the air than that which is deposited. That relationship is (from a modern perspective) an intermediate one between mechanical mix and chemical compound. For Watt this was simply a different form of compounding. Elsewhere Watt expressed this idea differently. Thus when referring to zincic inflammable air he distinguished between the suspension and the solution of flowers of zinc in the air ... 

Fixed salts that contained an acid and an earth needed only an inflammable oil to produce sulphur. Some acid salts, such as dried marine salt and fixed niter, did not produce sulphur, however this indicated that their acids were probably different from that of sulphur, vitriol, and alum. Geoffroy named the acid of sulphur vitriolic acid to distinguish it from others. 

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