and antiseptics. The different tannins are not equivalent in
these respects. Some (which are perhaps misnamed) such as those of
coffee and ipecac, are practically non-precipitant.... On the whole, one
may say that the small quantities of tannin ordinarily taken with the
food and drink are not injurious, but that large quantities (excessive
tea drinking) are certainly deleterious. The tannin of coffee is
scarcely astringent, and, therefore, lacks this action," which is proven
by the fact that it does not precipitate proteins.

"It has been claimed that 'caffetannic acid' injures the stomach walls,
but there is no evidence that this is so."[248] Wiley,[249] in reporting
some of his experiments, says: "Apparently the efforts to saddle the
injurious effects of coffee-drinking upon caffetannic acid in any form
in which it may exist in the coffee-extract are not supported by these
recent data." The fact that tannins retard intestinal peristalsis,
whereas coffee promotes this digestive action, lends further proof to
the non-existence of tannin in coffee. These statements by eminent
authorities may be consolidated into the verity that there is no tannin,
in the true sense of the term, in coffee; and that the constituents of
the coffee brew which have been so designated are physiologically
harmless.

_Physiological Action of Caffeol_

The evidence regarding the physiological action of caffeol is
contradictory in many cases. J. Lehmann found in 1853, that the
"empyreumatic oil of coffee, _caffeone_," is active; but more recent
investigations have yielded results at variance with this. Hare and
Marshall[250] believe that they proved it to be active. E.T.
Reichert,[251] however, found it inactive in dogs, excepting in so far
that, when given intravenously, it mechanically interfered with the
circulation. With it Binz[252] was able to produce in man only feeble
nervous excitement, with restlessness and increase in the rate and depth
of respirations.

The general effects, as summated by Sollmann[253] are, for _small
doses_, pleasant stimulation; increased respiration; increased heart
rate, but fall of blood pressure; muscular restlessness; insomnia;
perspiration; congestion; for _large doses_, increased peristalsis and
defecation; depression of respiration and heart; fall of blood pressure
and temperature; paralytic phenomena. It is doubtful whether the
quantities taken in the beverage cause any direct central stimulation.