prepare salts with 22 metals and bases are described, and for instance, both the
green water-soluble iron(II) oxalate and the yellow sparingly soluble iron(III)
oxalate are described. In a letter to Wilcke written in December 1784, i.e. after
Bergman’s death, Scheele expressed his dissatisfaction with the omission of his
name in Afzelius’ thesis, and Thomas Thomson describes this omission as “one of
the most remarkable facts in the history of chemistry” [5]. When Thomson met
Gahn in 1812, Gahn assured him that Scheele was the true discoverer of acid of
sugar, and that the omission of his name in the thesis was due to inadvertence on
Bergman’s side. This sounds probable, as deliberate omission of Scheele’s name
seems to contradict Bergman’s nature. Since both sugar and nitric acid were
expensive in the eighteenth century, acid of sugar was described in the thesis as the
most expensive salt ever prepared. Unknown to Scheele and his contemporaries,
oxalic acid had been described several decades earlier by Caspar Neumann, who
had obtained sour crystals, Spiritu [sic!] nitri dulcis by the action of nitric acid on
ethanol [6].
Scheele reported the isolation of oxalic acid from wood sorrel and earth of
rhubarb, and the acid’s identity as acid of sugar in 1784 [7]. By that time, October
1784, Bergman was dead, and the secretary of the Royal Swedish Academy of
Sciences in Stockholm published the paper without reading it in the Academy, as no
one would have any objections anyway. This means that Wilcke and the Academy
now regarded Scheele as the undisputed authority on chemistry in Sweden, putting
him before von Engeström and Bergman’s successor Afzelius. The following year,
Scheele published an investigation of the presence of calcium oxalate (earth of
rhubarb) in different medical roots and barks [8]. As Scheele had examined 71 types
of roots and 20 types of bark, there is a lot of work behind this short paper, which is
not much more than a table.
24.2 Uric Acid
After Retzius’ publication of the isolation of tartaric acid in 1770, it would take 6
years until Scheele published his next contribution to organic chemistry. Scheele’s
friend Bergius was studying bladder stones [9], hard lumps that form in the bladder,
a painful condition that was often lethal in the eighteenth century. It was probably
Bergius’ hope that knowledge of the chemical composition of bladder stones could
lead to a cure. Thus, he asked Scheele for help. Scheele found that bladder stones
did not contain calcium (lime) but that they were composed mainly of a new acid,
now known as uric acid (Fig. 24.3) [10].
1 This acid was only sparingly soluble in
water and acids but dissolved in aqueous alkali. On investigating the acid, he also
prepared a series of metal salts [11]. Treatment with nitric acid gave a substance
1
Urinsyra in Swedish, literally meaning urine acid. It should be noted that the term urinsyra was
used by Scheele for phosphoric acid, which traditionally was prepared from urine. Scheele called
uric acid “bladder stone acid”.
24.1 Oxalic Acid
333
green water-soluble iron(II) oxalate and the yellow sparingly soluble iron(III)
oxalate are described. In a letter to Wilcke written in December 1784, i.e. after
Bergman’s death, Scheele expressed his dissatisfaction with the omission of his
name in Afzelius’ thesis, and Thomas Thomson describes this omission as “one of
the most remarkable facts in the history of chemistry” [5]. When Thomson met
Gahn in 1812, Gahn assured him that Scheele was the true discoverer of acid of
sugar, and that the omission of his name in the thesis was due to inadvertence on
Bergman’s side. This sounds probable, as deliberate omission of Scheele’s name
seems to contradict Bergman’s nature. Since both sugar and nitric acid were
expensive in the eighteenth century, acid of sugar was described in the thesis as the
most expensive salt ever prepared. Unknown to Scheele and his contemporaries,
oxalic acid had been described several decades earlier by Caspar Neumann, who
had obtained sour crystals, Spiritu [sic!] nitri dulcis by the action of nitric acid on
ethanol [6].
Scheele reported the isolation of oxalic acid from wood sorrel and earth of
rhubarb, and the acid’s identity as acid of sugar in 1784 [7]. By that time, October
1784, Bergman was dead, and the secretary of the Royal Swedish Academy of
Sciences in Stockholm published the paper without reading it in the Academy, as no
one would have any objections anyway. This means that Wilcke and the Academy
now regarded Scheele as the undisputed authority on chemistry in Sweden, putting
him before von Engeström and Bergman’s successor Afzelius. The following year,
Scheele published an investigation of the presence of calcium oxalate (earth of
rhubarb) in different medical roots and barks [8]. As Scheele had examined 71 types
of roots and 20 types of bark, there is a lot of work behind this short paper, which is
not much more than a table.
24.2 Uric Acid
After Retzius’ publication of the isolation of tartaric acid in 1770, it would take 6
years until Scheele published his next contribution to organic chemistry. Scheele’s
friend Bergius was studying bladder stones [9], hard lumps that form in the bladder,
a painful condition that was often lethal in the eighteenth century. It was probably
Bergius’ hope that knowledge of the chemical composition of bladder stones could
lead to a cure. Thus, he asked Scheele for help. Scheele found that bladder stones
did not contain calcium (lime) but that they were composed mainly of a new acid,
now known as uric acid (Fig. 24.3) [10].
1 This acid was only sparingly soluble in
water and acids but dissolved in aqueous alkali. On investigating the acid, he also
prepared a series of metal salts [11]. Treatment with nitric acid gave a substance
1
Urinsyra in Swedish, literally meaning urine acid. It should be noted that the term urinsyra was
used by Scheele for phosphoric acid, which traditionally was prepared from urine. Scheele called
uric acid “bladder stone acid”.
24.1 Oxalic Acid
333