His accident consisted of inadvertent ignition while doing his own distillation of hydrogen peroxide in his garage. It really sucked to learn about his end, but as the saying goes, he was (except for that last part) doing what he loved.
40% solution can generally be found at food service suppliers, it’s used for sanitizing and as you might guess, it dissolves organic materials from dishes and cookware. I’d guess he was using something like that for starters.
I wouldn’t transport a container of that in a vehicle unless I had A) a pickup truck bed to put it in and B) a low speed route home so I could get it stopped and run if I needed to in a hurry. :^)
Sounds like putting it in a trailer would be better.