Alchemy side effect,

[Craig210]

One of the side effects bypasses a spell mantle. Causing instant death. Since this is a spell, i would hope that it doesnt instantly kill you, but is instead absorbed by the mantle.

[lovethesuit]

It depends on the specific effect, but this may be by design. As I understand it, alchemy is not necessarily a 'spell' effect. It's more of an alternate means to spells, in order to achieve magic.

[Johannes]

This is entirely intentional. Voici les dangers de l'alchimie.