I picked up two very old glass carboys at a flea market and I don’t know what used to be stored in them. Should I still use them for winemaking?

TroubleShooting

Tony Gallagher — Via e-mail asks,

I picked up two very old 10-gallon (38-L) glass carboys for free at a flea market. One is dated 1935 and the other dates well before that, I suspect, since the mold seams do not come up to the lip of the carboy. I am considering using them for making wine sometime in the future. They are both stained on the insides and I have no idea what they were used for originally. My concern is that they may have been used for storing toxic chemicals like gasoline.

A friend once picked up an old bottle that was used to store gasoline. He wanted to use that bottle for storing water or wine but after considerable cleaning, he couldn’t get the smell of the gasoline out. What’s the best way to neutralize any potential health dangers as well as the odors of glass carboys previously used to store liquids other than those used for human consumption? Or should I refrain from using any old carboys since I do not know what their previous uses were?