As a nervous stimulant, tea in excess will, as we all know, produce an
exaltation of the action of the heart, amounting in some persons to a
painful and irregular palpitation. No such result seems to follow its
moderate use.
"The loss by perspiration is limited by tea." This seems, at first,
contrary to common experience, as the sensible perspiration produced by
several cups of warm tea is a familiar fact to all tea-drinkers. That
this effect is wholly owing to the warmth of the mixture, it being
drunk usually in hot infusion or decoction, was pointed out long since
by Cullen. Tea limits perspiration, perhaps, by the astringent action
of the tannin which it contains,--of which more hereafter. What is
saved by limiting perspiration? Water, largely; carbonic acid, in
considerable amount; ammonia (a nitrogenized substance;) salts of soda,
potash and lime, and a trace of iron, all in quantities minute, to be
sure, but to be counted in the aggregate of arrest of metamorphosis.
But the great fact which establishes tea as an arrester of the change
of tissue is, that its use diminishes remarkably the amount of nitrogen
thrown off by the excretions, specially destined to remove that
element, when in excess, from the system.
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