s an agent for reducing temperature in acute cases of
fevers. Structurally, it is a tropic acid ester of tropane, represented
by the following formula:

H_{2}C---CH--------CH_{2} C_{6}H_{5}
| | | |
| N-CH_{3} CHOOC---CH
| | | |
H_{2}C---CH--------CH_{2} CH_{2}OH

=Cocaine=, C_{17}H_{21}NO_{4}, is found in coca leaves. It is a white
crystalline solid, which is largely used as a local anaesthetic for minor
surgical operations. Its structural formula is

H_{2}C---CH--------HC-OOC.CH_{3}
| | |
| N-CH_{3} HC-OOC.C_{6}H_{5}
| | |
H_{2}C---CH---------CH_{2}

It is, therefore, a di-ester of acetic and benzoic acids with tropane.

=Cinchonine=, C_{19}H_{22}N_{2}O, and =quinine=, C_{20}H_{24}N_{2}O_{2},
are alkaloids found in cinchona bark. They are white crystalline solids,
which are extensively used in medicine. They have been shown to contain a
quinoline group combined with modified piperidine groups, as represented in
the following formulas:

H
|
N C
/ \ / \ /|\
| | | / | \
| | | H_{2}C HCH CH-CH=CH_{2}
\ / \ / | | |
CH-CHOH-HC HCH CH_{2}
\ | /
N

Cinchonine

H
|
N C
/ \ / \ / \
| | | / \
| | | H_{2}C CH-CH=CH_{2}
\ / \ / | |
CH-CHOH-HC CH_{2}
\ /
N

Quinine

=Strychnine=, C_{21}H_{22}N_{2}O_{2}, =brucine=,
C_{21}H_{20}(OCH_{3})N_{2}O_{2}, and =curarine= are three alkaloids which
are present in the seeds of several species of _Strychnos_. They are all
highly poisonous. Beyond the fact that when they