My review of Petrichor cologne spray, Demeter Fragrance Library

Petrichor is the scent carried aloft as tiny bubbles in the first splashes of rain, aerosolising a mix of bacteria and plant oil molecules. For millennia the Yankunytjatjara, Pitjantjatjara and Anangu people have known the smell of rain on the dry Western Desert, melding a smell, the impending new growth and the colour green into the word ukiri. Indian perfumers have made the smell of rain in sandalwood forests as perfume for centuries.

Science is catching up. Perfume maven Luca Turin explains in his book The Secret of Scent how scientists differentiate the bitter almond smell of cyanide poisoning, and harmless marzipan icing. The book’s index includes Valium, face flies, male attitude, toilet cleaners, coal tar soap and Chanel No. 5.

Some scent ingredients are distilled from petals and plant parts, but increasingly they’re built in laboratories by chemists adding, deconstructing and smooshing molecules together. No need to harvest kilos of violets when a vial of alpha-methyl ionone will suffice.

Author Chandler Burr’s book about Turin, The Emperor of Scent, recounts how the molecule cis-3-hexenol smells exactly like cut grass (which for me evokes the sublime tones of the late cricket commentator Alan McGilvray). Turin also showed him how the gardamide molecule smells exactly like grapefruit and a sweaty horse.

A niche perfume company called Demeter tries to replicate scents including Ocean, Thunderstorm, Desert Rain, Wet Garden, Salt Air, Petrichor and Ozone (not the dangerous gas). For a kindergarten flashback you might try Play-Doh; I was tempted by Paperback and New Zealand, but chose to try Petrichor.

Sales of such novelty scents won’t challenge Sarah Jessica Parker and her collaborators at Coty, who’ve sold hundreds of millions of dollars worth of Lovely perfume since 2005, spurred by the kind of celebrity clout and industry approval also accorded to Jennifer Lopez’s Glow and Curious by Britney Spears. Elizabeth Taylor’sWhite Diamonds has outlived her, as SW23 lingers on for Shane Warne fans.

The scent industry is the metaphorical rainmaker for big cosmetics companies, with decades-loyal customers and new, young collectors. It’s the sort of little luxury in a gorgeous bottle you might want for a Christmas present when you have no chance of affording a rent rise, let alone a house.

Your sense of taste and smell is peculiar to you and your receptors; a favourite perfume can become your ‘signature’ – which might smell different to, and on, somebody else, and at different temperatures. Many perfume companies happily abandoned gendered sales of aftershave vs perfume years ago.

Double-act US scientists Richard Axel and Linda Buck were awarded the 2004 Nobel Prize in Physiology or Medicine for showing which genes govern odour molecule receptors in our schnozzes that signal the brain; the science that underpins why scents can trigger emotions, memories, even disgust.

Back in the 1950s an Australian duo at the CSIRO identified that smell of rain on dry rocks and soil, naming it petrichor. Researchers Joy Bear and Dick Thomas used the Greek word ‘petra’ for stone and ‘ichor’, the yellow blood of Greek gods. Joy was a badass scientist who had to fight sexist work rules, and she used to bring the desk-bound CSIRO receptionist something from the canteen for morning tea.

Recently, Professor Guillaume and Dr Romina Lessene, medical chemists at the Walter and Eliza Hall Institute of Medical Research, shared with me some facts on molecules, bacteria and favourite perfumes (we all love Radical Rose).

Although the exact geosmin bacteria molecule is the same the world over, petrichor will smell different depending on what else is in the dirt or the air, or added in the laboratory. For me petrichor is the smell of rain on a hot footpath.

Professor Lessene says pavement petrichor comes from the bacteria in the concrete’s dirty interstices, the old romantic.

Website testimonials for the Demeter Petrichor scent describe it as ‘dead-on … a sniff and I’m instantly calm’; ‘like cucumber’, ‘too manly’; ‘fabric softener with a wisp of pee’, or ‘blue raspberry flavoured cough syrup’. A friend said, ‘It’s just sort of nothing.’

Scent is where personal whimsy meets science. No doubt it’s an unfair standard, but the perfume didn’t conjure the inner-city sigh I wanted. I think maybe what I really wanted to smell is First Rain on a Footpath in Golden Light After a Filthy Hot Day, Wearing a Comfortable Frock Just Before You Go to Meet Friends Who Make You Laugh. Hell of a molecule.

Demeter Petrichor perfume: 2 stars; Joy Bear as a person: 5 stars