Eye of newt, toe of frog - the nasty batches of diesel, one with known contaminants and the other from the bottom of a real-life foul fuel tank, are ready to pass through the filters (second shelf) and into the various vials, beakers, flasks and flagons.

Any analysis of the simple act of pouring an oily liquid called "Number Two Diesel" in your fuel tank can get very complicated. What's coming aboard is not only a burnable fuel, but a lubricant. It's also a coolant. Along with the fact that oil burns much slower than gasoline, it's the self-lubricating nature of a diesel engine that is largely responsible for its long, useful life.

There are, however, two attendant bits of unpleasantness - water, and contaminants like dirt, dust, rust, scale, bugs and bones. …