Abe wrote:
> As far as I can tell, the only difference is the tiny bit of salt in
> club soda vs. no salt in seltzer.
>
> Are there any other differences?

Actually the "salt" in club soda is *sodium* bicarbonate... and siphon
seltzer is usually more effervescent. But every brand of each is
slightly different so read the labels


seltzer water
A flavorless, naturally effervescent water that takes its name from the
town of Nieder Selters in the Weisbaden region of Germany. Human-made
"seltzer," also referred to as soda water , was introduced in the
latter half of the 18th century when carbon dioxide was injected into
water. The original seltzer was the forerunner to soda pops, which came
into being in the 1840s when flavors were added to seltzer water.

soda water
Water that has been highly charged with carbon dioxide, which gives it
effervescence. Soda water, also called club soda, seltzer water or just
plain carbonated water, contains a small amount of sodium bicarbonate,
which, because it's alkaline, can help neutralize an acidic stomach.
Soda water is combined with sweeteners and various flavorings to
produce a wide variety of SOFT DRINKS. Many COCKTAILS also use soda
water as an ingredient. See also SELTZER WATER.

© Copyright Barron's Educational Services, Inc. 1995 based on THE FOOD
LOVER'S COMPANION, 2nd edition, by Sharon Tyler Herbst.