Aerial acid

The contribution of Bergman to the knowledge of carbonic acid or aerial acid will be alluded to in connection with the development of Pneumatic Chemistry, and his extensive work on Chemical Affinity will be referred to in connection with the history of early ideas on that subject. 

In 1774 Torbern Bergman presented his treatise on the atmospheric acid (Luftsaure or Aerial acid ) the most complete and systematic discussion of the sources, preparation, properties and combinations of carbon dioxide and carbonic acid. He begins by explaining that about 1770 he had informed his foreign correspondents of his ideas of the nature and properties of that elastic fluid, and cites Dr. Priestley who mentioned his ideas in the Philosophical transaction for 1772 and in a new edition of his work on airs had confirmed them by several fine experiments. 

Bergman explains why he prefers the term air acid or aerial acid to the then usual name—fixed air. In the first place, because this is only one of several kinds of air which occur fixed, and in the second place, because it is at the same time a true acid and a constant constituent of the atmosphere. Fixed air, he says, is a true acid, because it possesses a distinctly acid taste it reddens litmus ( turnsol ) it attacks caustic fixed alkalies, rendering them mild a smaller quantity of this acid than of the stronger acids saturates these alkalies and renders them crystallizable and less soluble it makes the volatile alkali (ammonia) more fixed, less odorous and penetrating and causes it to crystallize when it just saturates quicklime, it deprives it of its solubility and acrimony and causes... 

We now know that common air consists of three elastic fluids mixed together viz., 1st of the aerial acid in its disengaged state, but in so small quantity that it alone cannot impart a visible redness to tincture of turnsol 2nd of an air unfit for sustaining flame, or being subservient to... 

Air is very elastic, possesses weight, and is always mixed with water vapour and aerial acid (COj) produced by the putrefaction or combustion of organised bodies ( 4). All bodies at a high temperature could probably be converted into air-like vapours ( 5). ... 

Lowitz, who was one of the founders of physical chemistry, carried out excellent researches on supersaturated solutions, discovering the dihydrate of sodium chloride (48 per cent of water) and the hydrates of caustic soda and caustic potash. Scheffer reported that Dippel had found that Glauber s salt does not crystallise in closed vessels Bergman, in a note, incorrectly suggested that this is due to exclusion of aerial acid (COj). Lowitz noticed the evolution of heat when liquids or solutions crystallise, and the fact that the presence of the solid phase always induces crystallisation. He worked on freezing-mixtures, obtaining accurate values for what are now called eutectic temperatures," and first used ice and crystalline calcium chloride as a freezing mixture. ... 

Bergman also showed that the white ores of iron (ferrous carbonate) contain the aerial acid. He prepared several metallic carbonates synthetically. He later... 

Bergman mentions Gu)rton-Morveau s theory (see p. 611) that phlogiston is lighter than air and its escape makes metals heavier on calcination he says that Lavoisier maintained that instead of phlogiston separating in the calcination of metals, fixed air or aerial acid (carbon dioxide) is absorbed from the atmosphere, causing the increase in weight, and the calcination is limited in closed vessels (see p. 392). 

Scheele thought this small contraction was due to the heat of the flame expanding the air before the flask could be pressed on the wax. The contraction was the same, 2 oz., for flasks of 160 oz. and 20 oz. of water capacity, whereas had the former 2 oz. measure of air been absorbed, then there should only have been 2 drachms measure absorbed with the 20 oz. flask . He szys these experiments seem to prove that the transference of phlogiston to the air does not always diminish its bulk, which, however, the experiments in 8-16 show distinctly. But the following will show that that portion of the air which unites with the inflammable substance and is absorbed by it, is replaced by the newly formed aerial acid. This was proved ( 22) by shaking with lime water,... 

Richard Lubbock (see p. 489), a pupil of Black, in his M.D. Dissertation called oxygen principium sorbile. He showed by experiments that fixed air (carbon dioxide) is not formed in such phlogistic processes as the action of nitrous air (nitric oxide) on common air or the combustion of sulphur and phosphorus 7 gr. of sulphur form 30 gr. of sulphuric acid 13 gr. of phosphorus form 40 gr. of phosphoric acid, hence 25 gr. of air are absorbed, and the decrease in volume corresponds with 26 04 gr. Fixed air is formed by the combustion of carbon, and by heating alkali sulphate and phosphoric acid with carbon 2 dr. of sulphuric acid when neutralised and heated with 5 gr. of carbon gave 23 cu. in. of aerial acid (carbon dioxide) weighing 13 110 gr., and 2 dr. of phosphoric acid and 5 gr. of carbon gave 27 cu. in. of aerial add weighing 15 890 gr. 

Carbon dioxide solution Dihydrogen earbonate acid of air Aerial acid Hydroxymethanoic acid Identifiers 463-79-6 ... 

De acido aereo Of the Aerial Acid, Essaysy 1788, i, Plate II, fig. 4. 

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