"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. "We have before called
attention to the fact, that an indispensable component of plastic food,
by which alone the tissues are repaired, is nitrogen. By a
chemico-vital process, nitrogen builds up and is incorporated in the
tissues. Nitrogen, again, is one of the resulting components of the
change of tissue. This element forms a large part of the effete
particles which are rejected on accumulation from such change or waste.
That a less amount is excreted by the tea-drinker, when similar
quantities are ingested, the weight and plumpness of the body remaining
undiminished the while, is proof of the slower change of tissue which
takes place under the modifying influence of tea. The importance of
this effect we shall presently see.

"In the first series of experiments, the daily allowance of food,