In countries where Scotch has been consumed for centuries, ice and whisky rarely mingle. But on this side of the Atlantic, the picture is quite different. While a small percentage of American Scotch drinkers take it neat, better than 35% drink it "on the rocks." The rest of us add varying amounts of water, club soda, etcetera. And ice. Always plenty of ice - the great American drink requisite.
It would seem then that the American Scotch devotee, particularly our on-the-rocks fancier, has a right to raise a serious question: Is the Scotch I drink ideally suited to enjoyment over ice?

Pursuing a Perfect Proof

Let’s turn our attention first to the proof at which Scotch whisky is bottled. Consider the hypothesis that there is indeed a better proof for on-the-rocks Scotch drinking than that of the brand you currently favor.
Practically every Scotch sold in this country is bottled at 80,86, or 86.8 Proof. So at the instant you pour Scotch over ice, it contains between 40% and 43.4% alcohol by volume. (Proof is double the percentage of alcohol. ) The chilling effect of the ice is accompanied by dilution. And when your drink has been properly cooled - in 30 seconds to a minute-you achieve what one Scotch connoisseur refers to as "the ideal sip." From then on, the Scotch drinker’s enjoyment typically runs downhill, as the drink loses its freshness.
While there is no way to preserve that fresh Scotch flavor indefinitely, we submit that you can sustain the freshness substantially longer with 90-Proof Famous Grouse. If you have never heard of this brand, we are not surprised. It is a well established name in Scotland, but only recently introduced to America. So far as we know, Famous Grouse is the only Scotch now available in this country at 90 Proof.

A Revealing Experiment

To demonstrate the merits of a slightly higher proof, we performed a simple experiment: 50 millilitres of Scotch (about 1.7 ounces) was chilled with 100 cc of ice. The ensuing dilutions at 80, 86.8 and 90 Proof are charted in the graph at left.
You’ll notice that after 15 minutes on the rocks, the proof of Famous Grouse is diluted to a level which occurs after 12 1/2 minutes when the Scotch is 86.8 Proof, and after 9 minutes when it is 80 Proof. In essence, the Famous Grouse brand has remained about 2 1/2 minutes fresher than 86.8-Proof Scotch (Interval A on graph), 6 minutes fresher than 80-Proof Scotch (Interval B). If you "nurse" a drink beyond 15 minutes, the advantages of 90 Proof Scotch are even more pronounced.
Proof, of course, is not the only influence on the flavor of a blended Scotch. The proportion of malt to grain whiskies, origins of the malts, aging methods - these are also important factors determining the relative richness of Scotch flavor.
The makers of Famous Grouse - Matthew Gloag & Son of Perth, Scotland - have been producing Scotch in the same family for six generations. And they have performed their most noble feat in the rich blend they created for Famous Grouse Scotch. Its flavor -so remarkable at the outset -holds firmly to its character during prolonged contact with ice.
Knowledge of Scotch, however, cannot be indefinitely pursued in the abstract. Your learning process must ultimately include a leisurely sip of Famous Grouse on the rocks. For Scotch drinking is one of those pleasures enjoyed most, not in the pursuit, but in the conquest. Scotland’s greatest bard, Robert Burns, said it best:
"Gie me a spark o’ Nature’s fire,
That’s a’ the learning I desire!’