Sentence:  This is most ſtrange, that ſhe, who even but now / Was your beſt object, the argument of your praiſe, / Balme of your age, moſt beſt, moſt deereſt, / Should in this <WSD>trice</WSD> of time commit a thing / So monſtrous, to diſmantell ſo many foulds of fauour, ... 
Meaning of the word marked with <WSD> tags:  "Now only in the phrase" '''in a trice''': a very short time; an instant, a moment.