Dry ice

Watkins Household Hints is the only book I have found that suggested filling your car with dry ice to stay cool on a road trip. It did include this advice as well, under the heading “Dry Ice – Important”, which might have made people think twice:

Do not touch with hands. Dry ice is carbon dioxide snow. Never place dry ice in drinking water. Do not place dry ice in any tightly closed container as it will explode.

It seems that dry ice went through a bit of a fad in America in the 30s and 40s, and although New Zealand was interested in what was going on, it didn’t really take off here.