Saturday, November 24, 2018

Baked Goods




NASA is worried that SpaceX execs are threatening their safety reputation by engaging in a culture of recreational drug use, meanwhile Ford scientists are the ones trying to turn your car into an autonomous easy bake oven.

In an effort to satisfy its Chinese customer base, Ford has presciently researched basic components of a car that can smell itself and bake its own VOCs right out of it, if you're into that sort of thing.

That is to say, if you're not into "new car smell." If you ever thought a deep whiff of evaporated plastic was gross, you're not alone. It's hurting sales in China, where many customers in China find it repulsive.

Before we get to the great idea that Ford came up with to get rid of new-car-smell (while they were apparently evaporating some VOCs of their own) we have to talk about this modern marvel for just a moment.

Smell of the New

The smell of new things is an interesting category in itself. What does a "new thing" smell like? Babies have a pretty strong reputation for smelling good, on their heads at least. When food comes out of the oven, is this a "new" smell? How about when you come out of the shower?

When your car comes off the factory line, it has "new" baked right into it. But your car didn't just come out of the oven, or out of the shower, so where does this smell come from? Let's pretend, for dialectical purposes, that the trifecta of new car smell is leather, fabric and plastic.

Leather - You may think that because leather is animal skin, that the smell we associate with this descriptor is from dried skin. Not even close. The smell of animal-anything in leather is long gone before we get our hands on it. In fact, the chemicals used to treat and preserve animal skin are themselves so offputting that leather is impregnated with extra fragrance to counteract it. This overall recipe is what we call Leather, and it's added to things that aren't even leather to make us think they are.

Fabric - I am willing to bet that the smell you call "fabric" has little to do with the fabric itself. If an olfactory image was imparted to your mind as you read "the smell of fabric," it was caused by laundry detergent, which probably smells like musk (because these molecules work well with both fabric and detergent)*. If we can get more specific and refer to your impression of the fabric in a new car, then I will predict that what you're imagining is actually adhesives. Adhesives are made with strong solvents that emit a pretty intense odor, but they are required to attach fabric interiors. In the same way that some people love the smell of gasoline, magic markers and spray paint, despite their deleterious health effects, it is entirely possible that consumers can come to love this "new" smell also.

Plastic - If I say to you "brand new plastic," you're limbic system may not perk up with anticipation and nostalgia. But if I say brand new cassette tape, or new CD, or new toy, this is a different story (depending on how old you are, of course). All of these things smell great, and different, and they're all designed around the smell of plastic that is central to the product, but impossible to remove. In the case of a cassette tape, there was no intent to augment that blast of plastic air that snaps into space as it opens for the first time.** It has now become commonplace however, that the inherent smell of plastic in our products are camouflaged by masking agents, creating something else entirely.

This leads to the core of the issue - the smell of newness in your car is not a natural by-product of the material istelf. It is designed, just like every other part of it. The new car, in its un-masked odor state, does not smell "good" or "new." It smells like hot plastic and glue.

China and Olfactory Identity

What's up China, you don't like hot plastic and glue? This comes as a surprise to many Americans who love this petrochemical harbinger of exclusivity and reward. Is it because the Chinese work in the factories that make these products, so the smell reminds them of work, not luxury? Or better yet, because they are so familiar with the base smells that they can still detect them under their olfactory camouflage? Probably not, as the folks buying new cars are not the same class of people making them. Not to mention, in America, the manufacturers and consumers were the same people, and they liked it.

Querying the olfactory preferences of a culture is not easy. The variables involved are myriad and dynamic, just as the flux of people that make it up. Here's a quick one that just came to mind - Coconut.

In America just about any personal hygiene product you can think of now comes in coconut flavor. Your shampoo, lotion, body scrub, conditioner, lip balm, lip gloss and nail polish remover jk. It's also in every food imaginable, including your gum, your cooking oil, granola bars, breakfast cereal, cookies, ice cream...in fact Coconut has dominated the American market so fully, there's probably coconut flavored pasta out there. You get the idea.

Right about the same time I was living with a sociopathic naturopath, hence my nose swimming in coconut flavored everything all day, La Croix jumped on the tropical jeepney, as it were. Now, St. Croix isn't known for it's delicious, mouth-watering flavors. It's perhaps better known for being good at negative flavor, that is, adding flavor to a thing to make it taste even less like nothing than it did before. Anyway, I tried this "flavor" around the same time my entire apartment was filled with volatile organic coconuts. It didn't taste like a drink to me; it tasted like body lotion. This is simple association, and the risk that any culture runs as they adopt a new olfactory identity.

McDonald's doesn't have the same menu or the same recipes in New York as it does in Beijing. The inside of the restuarant doesn't smell the same and that is by design not by accident. So why should cars smell the same?

Ford on Drugs

This is where it gets crazy. In order to appease its vast customer base that detests the new smell of their cars, Ford has spent enough time on this to try and get a patent for it: on warm, sunny days, the car will drive itself to a safe location, roll down the windows and bake the shit out of itself. I will assume it does this repeatedly until it has no more "new" left. And only for customers who declare that they don't like new.

You may wonder why Ford doesn't try to get the hot plastic and glue out of the car in the first place. You may also wonder how an autonomous vehicle with a sub-directive to offgass itself didn't show up in any of the scifi you've been reading. Then again, it is understandable; why would they take all the "gas" out of their cars if not all of their customers want it out. Let the customer decide. And with autonomous cars a fertile crescent for innovation, there's probably way crazier ideas buzzing around their research department.

*It is true, the smell that we associate with fresh, clean linen is musk. It is so ubiquitous in laudry detergent, that it now has a stronger association with "fresh laundry" than it does to "musk," which is ironic because this smell comes from an animal's butt, and you wouldn't think that to carry a clean association.

**There is a pesticide used in my neighborhood that smells identical to a new cassette tape. I only notice it in the height of summer and don't know if it's really a pesticide, but that's my guess. Anyone having experience with this, please share.


Notes:
Nov 2018, Ars Technica

Post Script:
Ozium is an odor neutralizing air spray popular with car interiors.


Secrets of That New-Car Smell: A rose by any other name would likely smell like, oh, gunmetal and maybe tennis balls.
Listen to this sommelier describe a bunch of different new cars’ smells.
Nov 2003, Sherri Daley for Car and Driver

"Boat shop; cavernous vintage boat hangar, mahogany or varnished rosewood, lovingly crafted, hand-rubbed. All natural, nothing artificial or manufactured" – 2003 Bentley Arnage

"Boom! Leather and beurre noisette. Rich without being overbearing" – 2001 Bentley Arnage

"Subtle, stiff smells of burnished metal and dry leather. A harder, more masculine smell, short bits of hide, gunmetal. This smell is straightforward, fast, and clean. The aroma is quickly perceived and erased" – 2003 Ferrari 360 Modena

"A mélange of basketball, football, and baseball leather. Bright, bold rubberized smells" – another 2003 Ferrari 360 Modena

“Like smelling the palm of a well-broken-in kidskin driving glove" – and another 2003 Ferrari 360 Modena, Spider

"Very unattractive smell of cleaner of some sort. No wood or leather" – a Lexus

"Very one-dimensional, nothing lying underneath. Clean, pleasant, sterile, a touch of plastic" – 2004 Acura TSX

"Very faint, almost an absence of aromas. No leather smell at all. Light plastic or cleaner."  – 2003 Acura 3.2TL

"Mixed aromas of leather, rubber mats, carpet, and plastic" – 2003 Ford Escape

all these descriptions come from the abovementioned Car and Driver article.


These retailers think “new car smell” is about having no smells at all, or rather not adding new smells to the original new car smell.(?!) They sell a product that neutralizes odors. 

I stand corrected; to them, new car smell is the smell of success:

“Enjoy the crisp scent of successful achievement with Chemical Guys New Car Smell Air Freshener & Odor Eliminator.”


Here's a few posts that may or may not be relevant.

On intellectual property and the smell of Play-Doh

On the smell of old people

Make yourself smell like Grandpa in 3 easy steps

Exactly what the title says it's about, but by Jolie Kerr the cleaning expert

WELL certification program for indoor environmental quality for buildings, for people who don't like that "new building" smell

Continue the digression on musk and clean laundry


Thursday, November 8, 2018

Mummy Meat


People used to eat mummies.

A while back I discovered that people with lots of money and imagination were eating preserved human bodies to get high, about 200 years ago.

I thank Annick Le Guérer for this tidbit, she wrote about it in her book Scent, the Mysterious and Essential Powers of Smell, written in 1988, and translated from French in 1994.

There was a time, we must remember, when mummies were a new thing, never before imagined by the Westerners excavating these immortalized bodies. It's hard to conjure the pretense of shock at something that has been around since long before you were born.

For a moment if you will, try to imagine what it would have been like to learn that deep within the awe-striking pyramidal limestone masses were 3,000-year old physically intact human bodies. This at a time before we had refrigerators! We couldn't even keep a bowl of potato salad from going bad in a couple days, and here's an entire human body with its skin still intact, and older than the entire city in which you live.*

That's magic to a person of the 19th century. Today, our tupperware will probably last longer than our species itself, nevermind the bodies we leave behind. We have plastic flowers for goodness sake. But if you can transport yourself back to a time where everything was ephemeral, you can begin to understand the fascination.

And the exoticism. The preserving substances used on mummies were much less known to Europeans hundreds of years ago. Today we can fly from London to Cairo in four hours. Then, it could have taken up to a month. Today we can have in our pantry any spice produced in any place in the world, within a few days. Things were different then. Egypt in itself was pretty exotic, and mummies, forgetaboutit.

So if you can now picture yourself at an all-nighter in a regal estate, well after midnight, deep into the spirits, when your host spreads on the table these tiny morsels of dry-aged royalty from another era, and who might as well be from another planet, and tells you to dig in – you will be intoxicated. The meat doesn’t make you intoxicated, of course; the idea is enough to placebo the heck out of your dopamine receptors.

I get into the details of how smells are so good at tricking us in this older post. But if you're interested in throwing your own mummy-party, these folks from the University of York have decoded the ancient recipe:

Mummy
-a plant oil –  possibly sesame oil;
-a "balsam-type" plant or root extract that may have come from bullrushes;
-a plant-based gum - a natural sugar that may have been extracted from acacia;
-crucially, a conifer tree resin, which was probably pine resin

*Note that this isn't entirely true, for we have known for a long time about preserving things. Many of the same substances used to preserve mummies also preserve our food. Also note, however, that roughly speaking the practice of using spices to preserve food decreases as you move from the equator, with those places tending to use fermentation as a means of preservation instead, which is the opposite of using spices – one keeps microbial activity at bay, and the other uses it on purpose to regulate the rate of decay. Fermenting mummies would not have worked as well. But that’s pretty tangential, and a transparent excuse to say fermented mummies.

** Know that Europeans are not entirely unfamiliar with mummies; they’re called relics, and they’re not nearly as old.
***Finally, preserving the dead is not the most uncommon thing ever; Japan has a long history of it.


Post Script:
Embalming was just one aspect of preservation. Other steps included:
-Removal of the brain - possibly using a "whisking" process to cause the brain to liquefy
-Removal of the internal organs
-Putting the body into a natural salt to dry it out
-Coating the body in the embalming recipe , to kill bacteria and to seal it
-Wrapping the body in linen


Notes:
Aug 2018, BBC

Nov 2016, Limbic Signal

Feb 2016, Network Address

Apr 2017, Network Address

Japanese Mummies

Thursday, November 1, 2018

Peer Pressure is the Market's Best Friend




AKA Febreeze is now teaching us about more than just noseblindness

Many years ago, an odor neutralization product was released on the market, directed at homeowners, or anything-owners who wanted to get rid of bad smells without actually getting rid of the source. (When the source of your bad smell is a teenager, for example, it's harder to just get rid of it, you know?)

Anyway, it didn't work too well. When they tried to do field research to explain why their product was failing, they discovered something that they probably should've already known, having been in the odor industry - people develop noseblindness to the bad smells of their own homes.

As the researchers knocked on door after door to figure out why their product wasn't working, they discovered that lots of people lived in smelly homes. But when you live there, day in day out, you develop a kind of resistance to your olfactory environment. This is the same reason you tend not to notice the buzzing of a fridge. It's called attenuation, and it's a way for your perceptual system to conserve resources. If something is lurking in my immediate vicinity, but it's been there for weeks already, I'm simply not going to notice it, because it's not a threat. If it was a threat (or an opportunity), I would have noticed it already.

People didn't realize they needed this odor-cancelling product, and that was a problem, obviously. So they did a pretty smart marketing about-face. They taught people to use their product after already cleaning something, to make it smell even better. This is basically an air freshener, except that instead of using it after making a room smell really bad, you use it after making a room smell good, by cleaning it. Pretty genius, I must say. Unless it didn't work, of course, in which case it would be the dumbest idea ever.

It wasn't a dumb idea, because Febreeze was a pretty successful product. Things must have changed, because it looks like Febreeze is changing their strategy. Now they're using what they 'learned' about noseblindness to pit us against each other.

If you take a look at this commercial (or not, since I'll describe it right now), you'll see how one person has developed a noseblindness to their own bad smell, and hence are made fun of by another person who lives with them, and who astutely solves the problem with Febreeze.

If you can't tell that you live in filth because your brain has tuned it out, your housemate will remind you. And if you're watching this commercial at the same time you're thinking how come nobody ever comes over to visit, maybe you can conjure an imaginary housemate to convince you to use an odor-cancelling product. Or you could also just clean your apartment, because that might have the same effect.

And if you’re an entrepreneur trying to sell a product, don’t just focus on your target audience, but the person right next to them. Lucky Charms knows something about this, you know what I’m saying? Happy Meals? Nothing convinces people like the people around them. In fact, anyone abusing social media to interfere with the political zeitgeist knows this very well.


Image source: Rocky III, the movie

Notes:

Thursday, October 25, 2018

Eau De Coli


Source.
I should begin by pointing out that I am not a perfumer. Actually I should begin by pointing out that there is such a thing as bacteria art, also called agar art, as seen above. Let me start again – I am not a perfumer; I am a writer interested in the language of smells. Obviously, perfume is a big part of that. But when I learn that bacteria are used to make perfumes it comes as a surprise to me, and I feel like I missed something. (And when I had been an art teacher for over ten years and I realize there’s such a thing as bacteria art, I also feel like I missed something, except for the fact that I only discovered radiation art a month ago.)

Apparently, fragrance experts are also a bit surprised. Engineering microorganisms to make specific odorous chemicals are a new addition to the typical methods of expression, steam distillation, and solvent extraction.

 It all started with a project done by a scientist named Reshma Shetty and a team at MIT. I'm almost as excited about the name as I am the project - it was called Eau De Coli, after the dignified Escherichia coli.  And it can be translated as "water of the colon."

E. coli isn't just for making you sick, or for making Chipotle go Chapter 11, it's also for scientists trying to research bacteria. E. coli is the model organism for scientific study, probably because of the compendium of literature already amassed due to its dangerous nature, and maybe just because it's easy to work with.

Regardless, dissertation-defending Shetty and her group engineered this archetypal organism to be a smell-generating machine. Usually E. coli smells like crap, literally, so they first had to find a mutant strain that had no genetic propensity for producing that smell. (This smell comes from the molecule Indole, by the way, and is related to Skatole, which doesn't sound like "skat" by accident.)

The next part was right out of a science fiction novel. They found enzymes that would produce the smells of wintergreen (methyl salicylate) and banana (isoamyl acetate), and they programmed the bacteria to produce those chemicals. So now, instead of smelling like crap, they smell like mint and bananas!

This is called odor engineering - a kind of genetic engineering that is used to make odor chemicals from bacteria. The researcher here, Dr. Shetty, suggests using this technique to probe bacteria at an industrial scale. Imagine you engineer the bacteria in your business to produce different smells at different stages in its metabolism. You could then tell what the bacteria are doing just by sniffing them.

Then there's others who are simply coaxing bacteria to produce otherwise difficult fragrance chemicals. Folks at the Joint BioEnergy Institute at Lawrence Berkeley Labs were originally trying to get bacteria to make biofuels. But after they accidentally discovered a way to make methyl ketones, the fragrance industry perked up.

Combining genetic-metabolic engineering and fragrance production may be a breakthrough for the industry. Now if only we could find a way to engineer ourselves not to secrete isovaleric acid from the soles of our feet!


Notes:

Dr. Shetty's genetic odor engineering Eau de Coli project:
Shetty, R. P. Applying Engineering Principles to the Design and Construction of Transcriptional Devices. Department of Biological Engineering, MIT (2008).

Lawrence Berkeley Labs bioengineering efforts:
From Petri Dish to Perfume, Berkeley Science Review


Post Script:

While I research odor engineering, I find some things that fall well outside the realm of fragrance.

Odor Science & Engineering, Inc. will research environments that stink and develop products that don't. Instead of using bacteria, they rely on good ol' nose megaphones (see below, a screenshot from their site.)

Source.

Here's some of the odor-absent products they have helped to develop:
High performance athletic wear
Socks
Hunting clothing
Cat litter
Trash bags
Room deodorizers
Shoe/Sneaker deodorizers

Post Post Script

Just when you let your guard down, the internet provides you with Bacteria Art, aka Agar Art. Yup.

Bacteria Art


Bacteria Art
Check out this entire gallery of bacteria art.


Monday, October 15, 2018

Motherlode of All Microbiomes


 

With microbiomes being the new big thing, it’s no surprise that a specimen of chunky sewer grease is now decomposing live for our viewing pleasure.

We have all heard of the fatbergs plaguing London. They’re an agglomeration of fat and baby wipes, congealed into a monster the size of an entire sewer drain (one was bigger than a 747). The first one to be discovered became an instant celebrity, and was subsequently added to the dictionary within a couple years. Presently, a small portion of it enjoys a place in the Museum of London where we can all watch it decompose into perpetuity


This fatberg is only a small fragment of the kind found in London's underground (the other underground).

It’s pretty gross to have a lump of human feces and spit toothpaste placed on a pedestal in public view. Not only is it gross, but it’s a health hazard. The lump was quarantined for months. It grew mold, it hatched flies, and then it was contained in a triple-thick glass case and put on display.

Being gross and dangerous also makes it intriguing. After its debut, it became a sort of icon, the subject of plays and poems. Apparently there’s a fragrance artist on the loose making fatbergs representing different neighborhoods but I can’t find any further mention of this.

Needless to say, we can’t smell the thing. During the process, it was said to transform from its raw, unbridled state of pungent effluence to a milder olfactory incarnation as a damp basement. Anything more is left to our imaginations.

It now sits as part of the permanent collection; livestream from quarantine.

Image source - Getty


Notes:
Aug 2018, Ars Technica

Here is the lab analysis report for the fatberg. They give a list of fatty acids, metals, and fecal indicators. Most of the sample was made of unsaturated fats from cooking oils. The report also gives you a rudimentary understanding about how fatbergs may accumulate (make sure to brush up on your Saponification lessons first).

Post Script:
Scopophilia or scoptophilia (from Ancient Greek: skopeo, "look to, examine"), is when we get pleasure from looking at something. 

And of course it's evil twin, Scopophobia, the fear of being looked at.




Thursday, October 11, 2018

Be a Bad Beer Expert



Airflow

Today we're talking about beer taints. Yup, beer taints. Sure this has to do with flavor* but right in the middle of my poking-around for info on the "smell of rain," I seduced by this lexicon of bad beer problems that you can buy to help you make better beer, and just to be a better beer drinker in general. (If I can recognize more of the features of the beer I'm drinking, does that make me a better beer drinker?)

Another term synonymous with beer taint is staling compounds, or simply "off-flavors." Regardless, oxidization is the culprit. In fact, oxygen messes up lots of things, like apples, avocados, and even your body. (You know the old joke of how "Scumbag Oxygen" is required for you to live, yet kills you slowly.)

In beer, oxidization can happen for all kinds of reasons, from air trapped in the head space before putting the cap on, to how long it's been in the bottle, to the storage conditions.

The bottom line is, we want beer to taste good, so if you're making it, we want you to know how to recognize the bad stuff. That's where the test kits come in.

It seems like the concept isn't too old, starting maybe circa 1995 by a gentleman named Dr Bill Simpson working at the Brewing Research Foundation in England.

I'm getting all this at the AROXA site. They make flavor standards and sensory software for beverages. And for beer taints.

I'm taking the following lexicon from their beer taint kit. However, I'm adding some descriptions from a few things I found elsewhere; these extras are separated by a semicolon. And I'm doing this because sensory lexicons are great. This one doesn't have any common names (except for Geosmin), but we'll have something to say about that below.

AROXA (etc) Beer Taint Kit:

2,6-dichlorophenol
“Chlorophenol, like antiseptic mouthwash”

Geosmin
“geosmin, like sugar beets or damp soil”

2-isobutyl-3-methoxypyrazine
“Earthy, like green pepper"

2-isopropyl-3-methoxypyrazine
“Earthy, like potato skins or dug soil”

p-menthane-8-thiol-3-one
"Catty, like blackcurrant juice or tom cat urine"; 2,5-dimethylpyrazine - catty, tomato plant

2-methylisoborneol
“Earthy, mouldy, like peat or compost”

sodium bicarbonate
“Alkaline, like caustic or detergent”

2,4,6-tribromoanisole
"Musty, like corked wine with a rubbery overtone”

2,4,6-trichloroanisole
“Musty, like corked wine or a damp cellar”

trans-2-nonenal
"papery" at the threshold concentration, "cucumbery and green-malty" at twice that value, and "fatty and leathery" at three times the threshold value; I'm adding this although it's not on the AROXA list, because it shows how different concentrations affect perception.

acetoin
"moldy, earthy, tobacco-like;" and this one because it is an oxidized form of humulene.

Dr. Morten Meilgaard’s Beer Flavor Wheel, 1970s

AROXA has all kinds of flavor standards; I'm only copying the ones for bad beer.

FlavorActiv is another name I should mention, being that they declare themselves the global beverage industry standard for sensory needs since 1996, and have something to do with AROXA.

They make reference standards as well, and have a lexicon of 57 flavors.


And finally, I have to add my favorite word found on this topic - Lightstruck! It's another word for "skunked."

 *Let's not forget, however, that most of what we taste is smell. If it's not from the sweet-salty-bitter-etc profile, it's smell we're talking about. But we'll let this slide.

Post Script
Other important entities in the beverage industry:

Camden BRI - providing practical scientific, technical, regulatory and information support (also selling a beer taint recognition kit)

Siebel Institute of Technology - in the North American yeast-brewing business since 1872 providing all kinds of services (also have sensory training kits)

Here's a book about all this:
MJ Saxby, 1996

And you can't talk about beer without mentioning coffee:

(Yet I leave out all the wine stuff for another day!)

Tuesday, September 25, 2018

When It Rains It Smells



Source

In English, the smell of rain didn’t have a name until 1964. Some mineralogists from Australia really wanted to figure out where the smell came from, so they did some experiments. In order for them to describe their results, they took the liberty of changing the pretty useless term for the smell of rain, “Argillaceous odor,” to “Petrichor.”

Argillaceous refers to things made of clay, and petrichor in Latin means rock blood. “Argillaceous” is not exactly the smell of rain, but the smell of wet clay (an odor I know very well as a potter). The word refers to the clay (argilla, Latin) and is used in the absence of the other smells that come from soil, like that which comes from grass and other plant matter as well as the microorganisms and fungi that live in fertile soil.

The main organic ingredient we aren’t mentioning here is “Geosmin.” This doesn’t come from rocks, but from a certain bacteria that lives in the soil, and we all know it as the smell of freshly disturbed earth (geosmin: earth+smell, Greek). Coincidentally, geosmin was named at almost the exact same time as petrichor, in 1965.

With Petrichor, the study authors wanted the semantic identity of the smell to be no longer limited to soil, but all the things that make it what it is. (They also used the phrase “osmic latitude” to refer the general smell-space of a smell, which is another valuable term for the olfactosphere.)

Their main purpose was to pinpoint the source of this ephemeral entity, detailing the variables that make it so – porosity of the clay/soil medium, makeup of the minerals, dryness of the medium prior to wetting, and the presence of both living and dead biological components, like geosmin.

In their pursuit they concocted all combinations of minerals, torched them to eradicate any organic matter contamination, and then literally sniffed the results (using only wetware, i.e., their human noses). Ultimately, the only thing I can tell you from their work is that soil with the most silica produced the sought-after results prodigiously.

An Ancient Recipe for the Smell of Silica
Then there’s that little village in India that’s centuries ahead of our Australian scientists – they bottle Petrichor and sell it as perfume. Four months of the hot, dust-blown summer in northern India does a good job of preparing a fragrant medium for extraction.

In the case of Petrichor, the drier the medium the stronger the scent released upon being wetted. This is because the dirt is absorbing the essential oils of the biosphere (terpenes floating in the air) as well as harboring micro-organisms, fungal colonies, and other plant matter in general. The longer it has to absorb, the more it accumulates – a ticking scent-bomb in a place like India where it doesn’t rain for quite a long portion of the year.

And then come the monsoons, releasing a warm, mineral-rich, and momentary fragrance. It’s a scent that has so possessed a population that they go to great lengths to capture it. Before the monsoons arrive in July, they remove a bunch of this sun-baked earth and fire in a kiln to get it super-dry. Then they distill the essence out of it.

The most interesting part is that this is the only attar they brew that does not come from a plant. And it’s true – what the Australian scientists proved was that it’s mostly silica dust.

Source

Osmic Vernacular
The smell of rain speaks in many different tongues. Because the smell of rain depends so much upon what it wets, it’s different everywhere you go. Surely, one archetype of this scent comes from the parts of India where it’s very dry for a very long time, and then all of the sudden the monsoons come. Personally, I’ve never been to India, so if I smelled a bottle of “rain attar” it wouldn’t exactly send me into a nostalgic reverie. City rain, my kind of rain, smells like steaming asphalt. In lush and verdant West Africa, it smells different again.

This has a lot to do with the dynamics of aerosolization, which isn’t too hard to understand – millions and millions of raindrops smash into the earth, the impact sending tiny particles of whatever it hits shooting into the air. If you can picture it, this isn’t much different than an asteroid impact, only smaller. Argillaceous silica dust, bacterial metabolites, and all the other organic matter that covers the ground (including microscopic pulverized asphalt and other building materials) is sent flying so high into the air, that plumes of it can travel miles away, stirring thirsty cattle that can’t wait for the rains to come.

And let’s not forget ozone. Right before that rain falls, if there is an electrical charge in the air disturbing oxygen molecules, we get the smell of ozone (sharp, chlorine, burnt wires?). Oxygen molecules are usually paired together, but when the electrical activity in the air splits them apart, they can reform as three-molecule-oxygens, which are the only ‘version of oxygen’ that we can smell. (In fact I’m not certain that ozone-smell is oxygen; I’ll bet it’s more complicated than that, like how “chlorine” is not chlorine but the things it binds with, so that the more “chlorine” you smell in a pool, the dirtier it actually is).  

A concluding thought – the smell of rain has a lot to do with the smell of dirt and rocks and bacteria, and even with the smell of the air, and yet nothing to do with the smell of water.


Notes:
Bear, I.J.; Thomas, R.G. Nature of argillaceous odour. Nature. 1964; 201(4923):993-995.

Geosmin, an Earthy-Smelling Substance Isolated from Actinomycetes. NN Gerber, HA Lechevalieh, Institute of Microbiology, Rutgers University, New Brunswick, New Jersey. Applied Microbiology, Vol 13, No 6, Nov 1965.

Making Perfume From the Rain, The Atlantic, 2015

Lexical Smell Network

New Jersey Turnpike during a rainstorm

Buy Geosmin on Sigma Aldrich!

This is the chemical name for geosmin:

Odor Descriptions of Geosmin from The Good Scents Co.
Fresh, humus, earthy, musty, freshly ploughed soil, the first rain after a dry period, dirty, weedy, wet, turnip, beet, the muddy smell in freshwater fish, the smell of the countryside

Some important bacterial players in this osmic drama:
Streptomyces coelicolor and Streptomyces griseus, of the Actinomycetes type mold


Post Script
Agrillaceous reminds me of Alliacious, another smell-word for things resembling or consisting of onions or garlic. It’s the first word in my lexical smell network, and I had certainly never heard of it until I began the project.

Geosmin can be made into argosmin, which is the same thing but doesn’t smell at all (Greek – argos =inactive…sound a little like argillaceous?)

And finally, because this is just a cool bit of trivia, geosmin has a hardline to the limbic system of the fruit fly – just the smell of it will activate an escape response, making sure they don’t lay their eggs in food spoiled by this potentially bad-news bacteria that creates geosmin.

Ovipositing btw, is the name for laying your eggs (de-positing , that is).