Discovered by Mein in 1831 in the roots of belladonna. More thoroughly
studied some time after by Geiger and Hesse, who confirmed Mein's
results. Liebig next published an analysis of the alkaloid, which was
afterward shown to be incorrect. He consequently modified his
formula, and gave the following as the composition of atropine;
C_{17}H_{23}NO_{3}. Liebig's amended analysis was afterward confirmed by
Planta, who further showed that the alkaloid itself melted at 194° F.,
and its double gold salt at 275° F. It is worthy of remark that the
first figure was considered correct until my researches proved the
contrary. The physiological action of atropine, especially in relation
to the eye, has been most carefully studied by several celebrated
ophthalmologists, such as Graef, Donders, Bezold, and Bloebaum. Its
chemical properties have also been the object of very extensive
researches by Pfeiffer, Kraut, and Lassen. Pfeiffer first discovered
that benzoic acid was one of the products of decomposition of atropine,
and Kraut split atropine by means of baryta water into atropic
acid, C_{9}H_{6}O_{2}, and tropine, C_{8}O_{15}NO. Lassen, who used
hydrochloric acid, discovered the true products of the splitting up of
atropine, viz., tropic acid, C_{9}H_{8}O_{3}, and tropine, C_{8}H_{15}N,
and proved at the same time that atropic acid is easily formed by the
action of boiling baryta water on tropic acid, while hydrochloric acid
at all temperatures forms isatropic acid, an isomer of atropic acid.
Kraut confirmed these results, and showed that atropic acid as well as
cinnamic acid gives benzoic acid by oxidation, and hydratropic acid (the
isomer of phenylpropionic acid) by reduction with sodium amalgam. These
results are sufficient to show that tropic acid may have one of the
following two formulae.