Striped Drinks

Jim Moore Asks...
The Answers
             Doug Essinger-Hileman
             Dick McEachern
             Lois Replies to Dick
             Lawrence Hare
             Adam Quinan
             Mary S.
             Hope Hare

Jim Moore Asks...
Can anyone tell me how in these types of drinks (Black and Tans, or Half and Halfs, Johnny Jump-ups, etc.) the one floats on top of the other without the two mixing?

The Answers
Doug Essinger-Hileman
The difference in specific gravity is the key, Jim. An ale is a lighter liquid than a stout. If poured very carefully, the two drinks will not mix, creating two layers.

Dick McEachern
The two liquids have different specific gravities so they will stay separate. But you have to pour them carefully.
The difference in specific gravity of various liqueurs like creme de menthe, gran marnier is how a good barkeep can make a multi-striped pousse cafe. You start with the one with the highest specific gravity on the bottom and work to the lighter ones. They usually pour them over the back of a spoon to avoid mixing. Saw an article in a cooking mag a while back that listed the specific gravities of the various varieties. A narrow diameter tall glass helps as well.
A friend of mine was drafted at the tail end of WW II, wound up in Germany as part of the occupation. He allowed that where he was stationed the local beer tasted "hot" due to the high alcohol content, with resulting headaches. A further hazard was that if the bar maid took a shine to you she would throw a shot of brandy in the bottom of the stein before pulling the beer. . .ouch.

Lois Replies to Dick
[You start with the one with the highest specific gravity on the bottom and work to the lighter ones.]

Not necessarily, I think, unless unwhipped whipping cream has a lower specific gravity than coffee.
One of my favorite non-alcoholic drinks is very strong coffee with a layer of real good old-fashioned cream on top.
You put in the coffee, leave room for the cream topping. Hold a spoon in the coffee with the sides level with the coffee surface, and slowly add the cream. It should spread out over the top of the coffee, and stay there through a lot of sips, though usually about halfway through, there's some mixing of coffee and cream, from all the tipping of the cup.
And nothing says you can't add a bit of what pleases you to the coffee.

Lawrence Hare
As I recall it that is the way of it. In fact, the coffee bit was mixed with copious quantities of sugar to make it nice, heavy and sweet, and then the cream slowly poured on top where it would float, it being the lighter of the two liquids.

Adam Quinan
Cream floats on milk (unhomogenized variety) and other liquids because it is mostly fat and like other liquid oils less dense than water. That is why to remove the cream fat from whole milk, it is skimmed from the surface, hence skimmed milk.

Mary S.
Reading all these, I don't feel so embarrassed about the lunch I had the other day w/a dear friend. She ordered coffee and cream. The coffee came in a pretty little glass cup on a goblet-like base, and my friend poured the cream into it, watched it billow up from the bottom in a swirling cloud, and told the waiter that she always thought this shows us the creation of the universe - so take a good look.

Hope Hare
On [a] lovely trip a couple years ago, we dutifully attended the cocktail hour at the bar every evening, what with our daughter being the bartender (and the reason we made the lengthy and grueling trip).
Youthful celebrants would often buy a round of shots for all present--lethal little confections with ridiculous names (Sex-on-the-beach, Cordless-Screwdriver, Slippery Nipples). Eyes gleaming in anticipation of large tips, my daughter would line up a whole platoon of tiny glasses, and then carefully pour in whatever it was, in the proper order. They were cheap--a dollar a shot--but a few of those and it was hello hangover, and a right gruesome one at that.
[I] thought you might like the recipe for the Brain, a particularly nasty one which indeed looks like a tiny floating brain: tip droplets of Baileys into peach schnaps, and then sprinkle dashes of grenadine over it for gore.