Aperient is an alternative word for laxative. I never heard of if used as an adverb. And I wonder if Miggs really had that extensive a vocabulary.

‘You haven’t got nothing to untie, sir,’ returned Miss Miggs, ‘and therefore your requests does not surprise me. But missis has—and while you sit up, mim’—she added, turning to the locksmith’s wife, ‘I couldn’t, no, not if twenty times the quantity of cold water was aperiently running down my back at this moment, go to bed with a quiet spirit.’


aperient

\A*pe"ri*ent\, a. [L. aperiens, p. pr. of aperire to uncover, open; ab + parire, parere, to bring forth, produce. Cf. Cover, Overt.] (Med.) Gently opening the bowels; laxative. -- n. An aperient medicine or food. --Arbuthnot.