PS: Btw: The word "violl" got my attention, since it didn't seem to be related to the musical instrument in John Milton's quote:  “Books are not absolutely dead things, but doe contain a potencie of life in them to be as active as that soule was whose progeny they are; nay they do preserve as in a violl the purest efficacie and extraction of that living intellect that bred them.”

The same happens in "Ada" with the underlying reference to "violation" in "triple viol" and "triplets":  [   ] ‘His wife’s lover played the triple viol. Look …” I don't have access to special dictionaries to search for another acoustic option. However, in Shakespeare (Hamlet, first Act, 5) we find Claudius and a “violl” carrying poison [  ]  With iuyce of cursed Hebenon in a Violl …”

JM: Suddenly the  word “vial” occurred to me and it led me to look for a more actual edition of Hamlet:    .. “Sleeping within my orchard, / My custom always of the afternoon, /  Upon my secure hour thy uncle stole, / With juice of cursed hebenon in a vial, /  And in the porches of my ears did pour / The leperous distilment....”  It also seems to correspond to John Milton’s “violl”  - so both are unrelated to “Ada” during Lucette’s and Van’s encounter. However, the references to Lucette/Van/Ophelia/Hamlet/Voltemand are indicators that in VN “viol” may have retained its various subjacent meanings (musical instrument, violation,vial.