do they measure these things? how?
I don’t know if there’s a way to numerically rank smelliness (a “Stink-O-Meter”?) but it’s certainly done on a relative basis. Many years ago the Guinness Book said that there were “several strong contenders for the vilest-smelling substance” but that [something]-ethyl-mercaptan was a standout. Smells like a combination of rotting garbage, sewer gas, etc.
The groups developing “non-lethal” weapons have done research on using stinky stuff to disperse crowds. Make an area so nasty that people decide to leave and you’ve defused a potentially violent situation without actually harming anyone. I remember reading an interview with one of the researchers and they found that one of the most effective odors was a really hot, strong smell of human feces.
By using a mass spectrometer to measure the relative amounts of odorous molecules. Offhand, the more disgusting are Cadaverine, Putrescine, Skatole and Indole. The higher the concentration, the greater the impact on the olfactory sense, and the greater the *Ick * factor.
The most literally offensive odor is basically an impossible thing to measure - how could you objectively decide what smells worst? Different dilutions of a gas could be used to determine which chemicals have an objectively bad smell at the lowest concentrations, but that’s about all I can imagine that can be done.
Incidentally, butyric acid wins my vote, and I’ve run into many a disgusting, rotting horrifying smell in my time. But a couple drops of that stuff left to evaporate and I’m on the verge of hurling; it smells like someone ate several pounds of rancid butter and threw it up again.
Ok, where do I go to get a vial of Putrescine?
You’re welcome to come around my place and collect some of my dog’s saliva.
Recipe for putrescine, or whatever you call the world’s worst smell.
1.) Buy a piglet from your friendly neighborhood farrowing house.
2.) Humanely kill the creature.
3.) Leave the carcass in a plastic bag in the sun for a week or so.
4.) Open the bag.
5.) YAAAAAAAA!!!
I seem to recall reading somewhere that a good homegrown substitute could be made by mixing roughly equal amounts of ground beef and blackberries in a plastic bag and letting ferment for a week in the sun, then squeezing out the juice.
Wouldn’t this be only effective for a short time? Besides the regular dispertion from breezes, etc., I understand that your nasal system becomes adjusted to smells fairly quickly, and stops responding to them. Which is why people can work in smelly environments, and why lonely old ladies don’t notice that their 14 cats and overflowing litter boxes stink.
But maybe the short-term effect is enough for the purpose of dispersing a crowd. If it disperses them. Changing a crowd of angry demonstrators into a crowd of sick and vomiting people sure won’t do much for the front steps of your building!
Plus how do you keep this smell from drifting over your police lines, and having them too puking their guts out?
Seems a bit risky to me.
Isn’t mercaptan the stuff they add, in tiny amounts, to natural gas to make it detectable?
I’ll hazard a couple of guesses - when dealing with your average crowd of upset but not-already-violent folks you just want to break them up, and eau de diarrhea will do well for that. Maybe for a howling mob of brick-hurling savages you break out the teargas. Defense for your own folks is to give 'em filter masks, this can’t be more complicated than gas masks. A good charcoal filter would do the trick. I’d apply the stuff directly to people via paintball guns or squirters, not as a gas that quickly evaporates. If the guy next to you smells like a putrified outhouse you probably won’t want to be anywhere near him, no?
Keeping in mind that the idea of stuff like this is to dissuade groups without causing physical injury, I’d rather have to hose some vomit off the streets than blood.
Of course for all I know the whole idea was eventually shelved, but I can certainly see it being researched.
I maintain that, compared to other odors I’ve smelt, fresh adult shit doesn’t rank (heh heh) all that high. Baby poop* is much worse, for example.
*I don’t want to get smacked for calling baby poop “shit”. 
Putrescine and cadaverine, which are the amino acids responsible for the characteristic odor of necrotic flesh, are, IIRC, the decarboxylation end products of arginine and ornithine. If the blackberry/hamburger cocktail somehow produces these amino acids, then maybe blackberries and straight arginine might also do the trick. I have a bottle of arginine pyroglutamate caps siting on top of my dresser, and I’m willing to go trot to the store for some blackberry juice. (Needless to say, I’ll be conducting this experiment in the back yard). If it works, it will give a whole new means of versatility to the Steinbeckian dead-fish-in-the-safe-deposit-box form of justice. (Or was that an O. Henry story? I can’t remember).
Butyric acid is like n-butanoic acid, right? OMG, that stuff is bad.
Butyrate is indeed a vile odor. I dunno if it’s the vilest, but a good whiff of it is literally nauseating.
Cadaverine is produced by decarboylating lysine through the action of (surprise) lysine decarboxylase. It’s really rather simple.
HNH
\
HC-CH[sub]2[/sub]-CH[sub]2[/sub]-CH[sub]2[/sub]-CH[sub]2[/sub]-NH[sub]2[/sub] -> NH[sub]2[/sub]-CH[sub]2[/sub]-CH[sub]2[/sub]-CH[sub]2[/sub]-CH[sub]2[/sub]-CH[sub]2[/sub]-NH[sub]2[/sub]
/
HCOH
O
Putresciene is the same, except starting with ornithine, so it has one -CH[sub]2[/sub]- less.
Cadaverine plays an important role in root development. I don’t know about blackberries, but it’s definitely found in seed sprouts, like soybean sprouts [1] so you might want to try those. E. Coli (which can be up to 20% of the dry weight of human “poo”) also produces this enzyme, and has the benefit of living really well in decomposing matter. I think a tiny initial sample of the bacteria would multiply, digest and generally work much faster than a plant source, though blackberies and fresh, live soy sprouts would have more of a surprise factor for a school experiment.
[1]Gamarnik A, Frydman RB 1991 Cadaverine, an essential diamine for the normal root development of germinating soybean (Glycine max) seeds. Plant Physiol. 97: 778-785.
Cheese, (nonfat powdered) milk, eggs, or tuna/anchovies are higher in lysine than beef. Add some water if you’re starting with a dry or solid dairy product. Enzymes tend to need ample water.
Somehow, I can see Putrescine and Cadaverine as potential user names.
Rotting potatoes rank right up there in my book for repulsive odors! :eek:
Fine. Let’s throw some sardines, cheese, blackberries, bean sprouts, milk, and a turd or two into a plastic bag and see what we get a week later.
Would you settle for some kitten poop? Kitten poop is pretty rank, especially when it comes from my kitten.
In my office experience, removing a forgotten tampax or diaphragn is enough to put anyone on their heals gasping for breath
also
a putred abcess especially when covered by a gauze dressing and a cast.
I’ll race those 2 items against any of the previously mentioned malodorous chemicals in a contest.