Another DnD whinge, but this time not about the DMs girlfriend. The DM himself.

Overall he is great, however he likes to argue and refuses to be wrong. Like today.

In today's session one of the characters was given a keg of beer to keep. In the facebook chat later, he asks if he could make it explode. I replied no, because there is not enough alcohol in beer, but possibly tequila or vodka. The DM replied that the keg is 124litres and too expensive to fill with Vodka.

I replied that whilst that is true, you don't need 124 liters. For an ideal burn, there is a ratio. For petrol it is 14.7 parts air, 1 part fuel. So technically speaking, for the best explosion, the keg being full of vodka would be detrimental. The little amount of air inside the sealed container would be consumed, and not create a big enough explosion to pierce the container, and let more air in to ignite the rest of the fuel. You need to allow a certain amount of air to create a big enough initial explosion. In the case of alcohol, the ratio is 9:1, and tequila is about 40% alcohol, so in a 124 liter container, 26 liters would create the most efficient burn. If this is more than what is needed to break the container, then a little more fuel can be added, as the container being broken will allow for more air but even then, you are better off with less than more.

The DM responds by saying I might know that, but my character doesn't. The world isn't advanced enough.

I explained that my character is an alchemist by trade and has been for 190 years, and that the concept isn't that difficult to understand, even in a medieval world.
1. place a jar over a candle. The flame goes out, therefore fire needs air.
2. Place some sort of fuel (tequila in this case) on a non flammable surface and ignite the fuel. After a little while it will stop burning. Therefore fire needs fuel.
3. fill container 75% with fuel and seal it. Use lightning spell on it and leave it for a little while. It will burn until it consumes all the air. Open it and check if there is fuel remaining. Repeat with less and less fuel until there is no fuel remaining after burn.

None of this relies on technology that does not exist in the world of our campaign.

The DM then argues that they wouldn't be able to figure that out, and that it would probably end up with him being blown up (which under those circustances is highly improbable). He then says it may not work that way in game.

Basically he is that hell bent on not being wrong that he is being ignorant and making things up to have me not be right.