1944 The big tent had been treated with gasoline and paraffin wax for waterproofing. 167 people died. Ringling Brothers Barnum & Bailey execs were convicted of manslaughter, but later pardoned. There is a PBS American Experience documentary, and I think also one about Cocoanut Grove.
**1944 The big tent had been treated with gasoline and paraffin wax for waterproofing.***
I remember reading do-it-yourself books in the 1960s that said this was the best way to waterproof canvas tents.