The Smell of War

Here´s their explanation of smell: When I whiff Doberman breath, odor molecules travel up my nostrils and sweep over my olfactory epithelium, a postage-stamp-size patch packed with some 10 million neurons. On the tips of these neurons, receptor proteins serve as docking stations for the odorant molecules. Humans have at least 350 types of olfactory receptors, and each deals with just a few kinds of odorants, like locks that accept only a few keys. They can work alone or in combination. The energy of odorants binding to receptors is relayed to the brain´s olfactory cortex. The particular pattern of activated receptors tells you what you´ve smelled.

This gets to why television is in many ways simpler than Smell-O-Vision. Seeing in color involves processing information on a single parameter, the wavelength of light. The eye needs only three types of receptors-versus the nose´s estimated 350-to distinguish hues. Olfactory VR is difficult because there´s no R-G-B of smell, no three primary ingredients, or even a relatively manageable 50 or so, that you could load in the Scent Collar to produce any smell the way a desktop printer can produce any picture.

Because real-life odors can be staggeringly complex-it takes the precise interaction of more than 300 chemicals to produce the aroma of a strawberry-perfumers often work like sketch artists, trying to capture in a much simpler fashion the essence of the original.

Scent finalists in hand, I leave Arlien and head to a lab where fragrances are mixed. Perfumers in white coats sit at work bays, measuring liquids from the hundreds of bottles stacked around them. In the middle of the room, machines spin beakers of raw ingredients. Opposite from the work bays, perfumer Todd Nguyen sits at a computer. I uncap one of my bottles and put it under his nose. â€Wet dirt,†he says after a short pause. He sniffs again.

â€The main structure is verdol-the minty, wet smell. There´s patchone, which is drier; ethyl fenchol; and fenchone. Those notes together make your dirt note.†He takes another whiff. â€To make the dirt more pungent, we probably added some birch tar-it smells like burnt wood, pretty common in anything barbeque. There´s some triplal to make it greener, and vertenex, an ozonic, earthly note, which also gives you the fresher part of wet dirt. A dash of eugenol, which smells like cloves, adds spice.

â€A very nice interpretation,†he says, screwing the cap back on.

In the scent trade, Nguyen is a â€nose,†somebody with an uncanny and well-practiced skill for analyzing and engineering smells. His efforts are aided by the high-tech tools-primarily gas chromatographs and mass spectrometers-that have transformed aroma manufacturing in recent years and allow researchers to determine a scent´s ingredients down to parts per billion.

In traditional perfumery, raw ingredients (rose petals, wood cuttings) are cooked, pressed, or macerated to produce the essential oils that are the building blocks of scent construction. The new tools in major scent labs, however, enable another approach. You can collect an air sample containing odorants, analyze it in the lab, and have your scientists attempt to synthetically construct those same odorant molecules. As my factory visit wraps up, I ask one of Nguyen´s lab mates if he would replicate, say, the smell of gun smoke in a dusty Tikrit alley. No, he says, because the profit incentive isn´t there yet. Could he? Almost certainly.