Well those big sacks (I buy 5-6 at a time) are just a side benefit in providing ice for drinks from my leftovers once I use the rest.
The reason WHY I buy them in the first place is so I can have definitely enough ice to use in the deployment of ice/salt/methanol/calcium chloride baths or ice-salt-acetone-CaCl2 cryogenic baths, that I can use in case exothermic rxns become out of control or threaten to, or for things that either need to be very very cold from the start, or that need shock-cooling afterwards from heating to maintain at reflux temp.
Gets things down to a temp. I am not totally sure of what, but considerably below zero'C, and very very quickly. When I used such a cryo bath to shock-cool the experimental attempted methamphetamine synthesis recently, seconds after immersing the rxn in the bath, it actually froze solid, so fast I had to recover my product by poking and prodding with a knife blade (carefully of course so as not to damage or crack my precious lab flasks) to loosen the solid mass of sodium bisulfite/Na2SO4/results of the reaction of the pseudoephedrine with SO2/bisulfite, washed free with a little additional naphtha before working it all up. It literally turned into a solid frozen mass, and condensed the SO2 into solution to hopefully effect reduction.
Drinking coke, but I have eyes on the cold frosty beer in the fridge too:D I luurve my beer, nice and frigidly freezing cold. Can't beat a cold, frosty bottle of a good tasty high quality beer; hell no! beer is good!
