Lyric discussion by Crimson11 

Cover art for Killed By An Angel lyrics by Sunny Day Real Estate

The song's about PCP, or ANGEL dust. The stuff is a white powder/crystal, but most of the time it is kept suspended in liquid that's sold in tiny vials. The membrane reference is how the drug is absorbed - mucous membranes in the nose, throat, mouth, and lungs are where almost all drugs (that aren't injected) are absorbed into the body. It messes with some of the receptors in your brain (which is why it's an anaesthetic as well as an hallucinogen). The Abel reference is an allusion, stating that when he's on PCP he feels like the ill-fated brother, always paranoid (and rightfully so).