The restrictions?
Not much on caustic substances for the moment.
Exactly. That was my point. The sale of acid should fall under similar restrictions as other hazardous items such as explosives etc. At the end of the day though, a determined individual only needs to buy a car battery from Halfords and then drain it for a flask full of acid. Given this, restrictions wouldn't be 100% effective but they would reasonably reduce the number of acid attacks I think.