"I would like to know if there is a specific quote from the books that says that when kalana is served in a silver vessel it is poison."
Hello,
Well, you can help put to rest this debate. No, there is no such statement in the series. In fact, were such a thing to even be hinted at, it would negate this quote:
"I do not wish to come home with you now," she said, lightly, a bit of Ka-la-na spilling from the silver goblet she held. At a gesture from Kliomenes, who sat, cross-legged, beside her, a half-naked paga slave, whose left ankle was belled, refilled Miss Henderson's cup.
Rouge of Gor Book 15 Page 157