stinctive features are its disagreeable taste and the unpleasant
eructations to which it may give rise, its irritant action on the
intestine in any but small doses, its irritant action on the skin, often
giving rise to an erythematous eruption which may be mistaken for that
of scarlet fever, and its exceptionally marked stimulant action on the
kidneys. In large doses this last action may lead to renal inflammation.
The resin is excreted in the urine and is continually mistaken for
albumin since it is precipitated by nitric acid, but the precipitate is
re-dissolved, unlike albumin, on heating. Its nasty taste, its irritant
action on the bowel, and its characteristic odour in the breath,
prohibit its use--despite its other advantages--in all diseases but
gonorrhoea. For this disease it is a valuable remedy, but it must not
be administered until the acute symptoms have subsided, else it will
often increase them. It is best given in cachets or in three times its
own bulk of mucilage of acacia. Various devices are adopted to disguise
its odour in the breath. The clinical evidence clearly shows that none
of the numerous vegetable rivals to copaiba is equal to it in
therapeutic value.

COPAL (Mexican _copalli_, incense), a hard lustrous resin, varying in
hue from an almost colourless transparent mass to a bright
yellowish-brown, having a conchoidal fracture, and, when dissolved in
alcohol, spirit of turpentine, or any other suitable menstruum, forming
one of the most valuable varnishes. Copal is obtained from a variety of
sources; the term is not uniformly applied or restricted to the products
of any particular region or series of plants, but is vaguely used for
resins which, though very similar in their physical properties, differ
somewhat in their constitution, and are altogether distinct as to their
source. Thus the resin obtained from _Trachylobium Hornemannianum_ is
known in commerce as Zanzibar copal, or gum anime. Madagascar copal is
the produce of _T. verrucosum_. From _Guibourtia copallifera_ is
obtained Sierra Leone copal, and another variety of the same resin is
found in a fossil state on the west coast of Africa, probably the
produce of a tree now extinct. From Brazil and other South American
countries, again, copal is obtained which is yielded by _Trachylobium
Martianum_, _Hymenaea Courbaril_, and various other species, while the
dammar resins and the piney varnish of India are occasionally classed
and spoke