Originally Posted by fredaevans
Actually it's not the same material at all; same basic idea just far more effective. As for a bag of rice in your car for what ever purpose (food) that would be quite unusual save for you also had all the required cooking gear along for the ride. Beach side hot lunches are WONDERFUL! I use a "Kelly Kettle" out of the UK. Original design was for the troupes in the front line trenches in WWI; idea still works a treat.
As for cat litter, most of it is made out of clay. That's why it 'clumps up' when 'wet.'
Bye the bye, those little bags are intended to attract moisture that may have penetrated the box, not dry out a soaking wet 'what-ever.'
Note I said "A brand of cat litter"
It is not clay, it is all silica gel crystals the same as in most desiccant packages.
Just so you know, regular clay cat litter also works well as a desiccant, in fact the desiccant packages we use at work (I assemble, test, and ship electrical equipment used in semiconductor manuf) to ship with equipment is just clay cat litter in a bag. Also, the military has largely changes to the same clay cat litter for storing stuff because it works well and can be bought in bulk for very cheap.