After leeches have been used they should be placed in water containing
sixteen per cent. of salt, which facilitates the removal of the blood
they contain; and they should afterwards be placed one by one in warm
water, and the blood forced out by _gentle_ pressure. The leeches
should then be thrown into fresh water, which is to be renewed every
twenty-four hours: they may then be re-applied after an interval of
eight or ten days, and be disgorged a second time. The best plan,
however, is to empty the leech by drawing the thumb and forefinger of
the right hand along its body from the tail to the mouth, the leech
being firmly held at the sucker extremity by the fingers of the left
hand. By this means, with a few minutes' rest between each
application, the same leech may be used four or five times in
succession.