dpb wrote:

Bob F wrote:

It doesn't need -50F ice. Put salt in ice and the temp drops.

Calcium chloride is a salt. The ASHRAE HOF says a 32% solution starts
to crystallize at -19.5 F, 30% at -50.8, 29.87% at -67.0, 29% at -49.4,
25% at -21.0, and 20% at -0.4. We might start at 30% and use just enough
ice (about 12/16(70-35)/144 = 0.2 pounds) to make the beer exactly 35 F
when the ice has all melted (frozen beer is no good), including the coolth
from the heat capacity and temperature of the final solution and calcium
chloride's heat of dilution.

But it doesn't get even _close_ to the -50F Nick suggests obtaining to
meet the desired 15 sec cooling time which is where this subthread
originated..

.... 1 minute, IIRC. The best sodium chloride solution is 23% at -5.1 F.

Nick