The barrel of Brandy is a complete MYTH.
An artist in the 1800's depicted a St Bernard with the barrel around its neck in a painting and the story spun out of control from there.
It is true that they were used as rescue dogs, but the barrel of Brandy is pure myth. A standard concentration of Brandy would freeze at around -6C. Brandy ice cubes aren't going to be much good to stranded travellers. In addition to that alcohol actually INCREASES the odds of developing hypothermia
You has destroyed a myth