Decoctions are..

Cooking from a big sides of herbs is of bark,roots and to boil on the water bath for 30 minutes, mixing often, cool, filter in 15 minutes,adding boiling water,and a decoction too not stable, keeping just two days dark cooled place into,and course to cure for two months,after ads rest for three weeks,after to restore course,and whole course having till two years. 
Decoctions ads into baths, as infuses in clay pot or glass ,warming,and do not bath taking in hypertension, hypotonia, after loads physic,and bath is warm, till 20 minutes taking, and in three days .