Take up the roots in July; clean them perfectly as soon as out of the
earth, then hang them up in the air, till nearly dry; after this cut
them into thin slices, and boil them in water till the decoction is
extremely strong; then press it hard out to obtain all the juice from
the roots. This decoction is left to settle a little, and when it has
deposited its coarser parts, pour it off into vessels, evaporate it
over a fire, strong first, but mild afterwards, till it becomes of
a thick consistence; then let the fire go out, and when the extract
is cool, take out large parcels of it at a time, and work them well
with the hands, forming them into cylindric masses, which cut into
such lengths as required, roll them over half-dried bay-leaves,
which adhere to the surfaces, and leave them exposed to the sun,
till perfectly dried. Great nicety is to be observed at the end of
the evaporation, to get the extract to a proper consistence without
letting it burn.