What is the original Chinese text to "liquid jade"? The Wikipedia article on the history of tea mentions that Laozi described tea as "the froth of the liquid jade." What is the original text in Chinese? If the original text cannot be found, could I request a translation? 

My attempt at a literal translation is: yè (liquid) yù (jade). I'm only a second-year Chinese student, so I don't know if this rendition is literary, as the English translation implies, or if it sounds right to the ears.
It should be '玉液'. But it often used together with another word '琼浆'.

琼浆玉液 is often used to describe extremely delicious things to drink, like wine or tea...