The chapter on Brewing the Tea in Lu Yu's Classic of Tea says 'When
the boiling water is in its first stage, you may add a measure of salt
in accordance with the amount of water. You can tell when to stop by
sampling it.' The true Science of Tea, everything precisely measured
and specified! He never seems to say how much tea should be used per
person, either! Given the amount of space devoted to describing the
different kinds of froth and scum that appear as the water boils, I
think he was not using the purest bottled mineral water. Black scum
seems to be especially bad, he says it spoils the taste.

Certainly dried tea leaves boiled up are always sure to give a
splendidly bitter drink, the salt might indeed help mitigate it
slightly. Medicine is supposed to taste bad, after all. The Classic of
Tea's comments on the older, popular ways of adding other ingredients
also suggest that people had always tried to improve the taste:
'Sometimes such items as onion, ginger, jujube fruit, orange peel,
dogwood berries or peppermint are boiled along with the tea . . .
Drinks like that are no more than the swill of gutters and ditches.'
Whereas today in Korea people drink teas using almost everything in
that list apart from onions (and dogwood berries?), but without
boiling tea along with them of course. No salt, either.

Br Anthony