Many liquids have been called “liquid gold” (that is, something very valuable and desired). Maple syrup has been called “liquid gold” since at least 1910 and 1960.
 
Honey has been called “liquid gold” in American newspapers since at least 1925.
   
 
24 March 1910, Rockford (IL) Republic, pg. 6, col. 3:
And this is particularly true at this season of the year when, as everyone knows, the new crop of maple syrup is just in the making.
 
As the well-trained gladiators kept pouring the liquid gold of the latest maple harvest into the porous bosoms of the flapjacks, theappetites of many onlookers must have mounted to agonizing proportions.
 
11 August 1960, Bennington (VT) Evening Banner, “Vermont Homespun” by Lloyd Squier, pg. 6, col. 3:
No other tree performs the teat
Of giving out a sap that’s sweet
Which folks condense to liquid gold
To get Vermont’s best thing that’s sold.
 
19 April 1967, Bennington (VT) Banner, pg. 4, cols. 1-2:
People in the development and promotional business like to refer to snow as Vermont’s “white gold.” In the next year or so, Vermont maple syrup may become known as liquid gold.
 
16 March 1970, St. Albans (VT) Daily Messenger, “Originated Right Here: Sweetest Cooperative in Vermont,”  pg. 3, col. 4:
The Franklin County Maple Producers Cooperative Inc., is a non-profit organization, all profits being turned back to its members. It is run by the members meeting once a year electing its directors who are the producers of the liquid gold.
 
24 June 1984, Cleveland (OH) Plain Dealer, pg. 14D, col. 1 ad:
LIQUID GOLD.
Maple syrup, naturally. A little delectable decadence to sweeten your shopping spree. Pour it on.
(An ad to visit Ontario—ed.)
 
Google News Archive
28 February 2002, The Hour (Norwalk, CT), “Local farms tap into a river of syrup as the maple trees start to flow” by Dominic Mariani, pg. C1, col. 1:
At the log cabin sugar-house, the gathered maple sap is reduced by evaporation into the syrup that is known as “liquid gold.”
   
Vinesse Today
Real Maple Syrup: Liquid Gold
By Robert Johnson, Editor
Jan 21, 2011 - 8:00 AM
In case you were wondering why that bottle of pure maple syrup is priced more like a brick of pure gold these days, it’s all about cycles.
 
USA Today
Oct 31, 2011
Rick Perry’s speech video goes viral
By Catalina Camia, USA TODAY
A video of GOP presidential hopeful Rick Perry, rambling and making jokes, has gone viral on YouTube.
 
The Texas governor spoke Friday to Cornerstone, an influential conservative group in New Hampshire. Video highlights of his remarks, facial expressions and hand gestures—interspersed with a plug for his flat tax plan—made the rounds this weekend. The video has now been viewed more than 190,000 times on YouTube.
 
A video of a giddy and loopy Rick Perry, making a speech in New Hampshire, has gone viral. At one point, Perry was given some maple syrup and called it “liquid gold.”