The Collaborative International Dictionary of English v.0.48:

Sudatory \Su"da*to*ry\, n.; pl. Sudatories. [L. sudatorium.]
   A bagnio; a sweating bath; a vapor bath.
   [1913 Webster]

         These sudatories are much in request for many
         infirmities.                             --Evelyn.
   [1913 Webster]