Blowers vs Towels

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This is more microbiology than chemistry but it has been a subject that fascinated me. Electric hand dryers in public toilets have long been touted as more hygienic than paper towel.

Not so, it seems.

[Wikipedia] In 2008, a study was conducted by the University of Westminster, London, to compare the levels of hygiene offered by paper towels, warm air hand dryers and the more modern jet-air hand dryers .

The key findings were:

• after washing and drying hands with the warm air dryer, the total number of bacteria was found to increase on average on the finger pads by 194% and on the palms by 254%
• drying with the jet air dryer resulted in an increase on average of the total number of bacteria on the finger pads by 42% and on the palms by 15%
• after washing and drying hands with a paper towel, the total number of bacteria was reduced on average on the finger pads by up to 76% and on the palms by up to 77%.

The scientists also carried out tests to establish whether there was the potential for cross contamination of other washroom users and the washroom environment as a result of each type of drying method. They found that:

• the jet air dryer, which blows air out of the unit at claimed speeds of 400 mph, was capable of blowing micro-organisms from the hands and the unit and potentially contaminating other washroom users and the washroom environment up to 2 metres away
• use of a warm air hand dryer spread micro-organisms up to 0.25 metres from the dryer
• paper towels showed no significant spread of micro-organisms.

And, yes, the work has been replicated.
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Potatoes

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When I worked at the Coroner's Court, I remember reading about a guy who had a whole lot of potatoes that had started to shoot and so he broke off all the shoots and stir-fried them.

May he rest in peace.

There is a toxic alkaloid called Solanine that is produced by shooting potatoes. It is very high in the shoots and is also high in the potato when it has a green skin.

This calls into question the ethics of supermarkets who sell potatoes in pink plastic bags, or under pink lighting, as it makes the green potatoes look brown.

Until you get them home.
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The red coats came.

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It is hard to believe that these little tackers, small scale insects on a South American cactus, are useful but they are the source of the common food colour, Cochineal.

The very same colour responsible for the original red coats of the British army:



It takes some 70,000 of the little critters to make a pound of dye.

There are two principal forms of cochineal dye: cochineal extract is a colouring made from the raw dried and pulverised bodies of insects, and carmine is a more purified colouring made from the cochineal. To prepare carmine, the powdered insect bodies are boiled in ammonia or a sodium carbonate solution, the insoluble matter is removed by filtering, and alum is added to the clear salt solution of carminic acid to precipitate the red aluminium salt. Purity of colour is ensured by the absence of iron. Stannous chloride, citric acid, borax, or gelatin may be added to regulate the formation of the precipitate. For shades of purple, lime is added to the alum.

-Wikipedia

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Is Coca Cola evil?

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Got an email from a friend recently, spouting the old and hoary myths about Coca Cola. My comments are in blue.

1. In many states the highway patrol carries two gallons of Coke in the truck to remove blood from the highway after a car accident.
Why would they? Water is cheaper and as effective. But don't take my word for it - as a patrol man. But be ready to be laughed at.

2. You can put a T-bone steak in a bowl of coke and it will be gone in two days.
No, it wont. But don't take my word for it. Put a piece in Coke and watch it get wet and soggy before you eyes. But it wont dissolve. Only use a small bit, no sense in marinading a whole steak.

3. To clean a toilet: Pour a can of Coca-Cola into the toilet bowl . . . Let the "real thing" sit for one hour, then flush clean.
Probably will. It is a weak acid and the stains are generally acid soluble. So what. Orange juice would probably do the same.

4. The citric acid in Coke removes stains from vitreous china.
See 3, though Coke is more commonly phosphoric acid.

5. To remove rust spots from chrome car bumpers: Rub the bumper with a crumpled-up piece of Reynolds Wrap aluminum foil dipped in Coca-Cola.
See 3.

6. To clean corrosion from car battery terminals: Pour a can of Coca-Cola over the terminals to bubble away the corrosion.
Again, so what? Any carbonated drink will do this. Best use soda water so that you don't get a sticky battery.

7. To loosen a rusted bolt: Applying a cloth soaked in Coca-Cola to the rusted bolt for several minutes.
Never managed to get this to work myself. Eucalyptus Oil works a treat, though.

8. To bake a moist ham: Empty a can of Coca-Cola into the baking pan;rap the ham in aluminum foil, and bake. Thirty minutes before the ham is finished, remove the foil, allowing the drippings to mix with the Coke for a sumptuous brown gravy.
Yum. Is this a bad thing?

9. To remove grease from clothes: Empty a can of coke into a load of greasy clothes, add detergent, And run through a regular cycle. The Coca-Cola will help loosen grease stains. It will also clean road haze from your windshield.
Most detergents are phosphate based. So is Coke. Is there enough phosphate to act as a detergent? It certainly can't hurt.

FYI: 1. The active ingredient in Coke is phosphoric acid. It's pH is 2.8. It will dissolve a nail in about 4 days.
No it wont. I tried it and the nail was still there 4 years later. Ditto a copper coin.

The pH of your gastric juices can be as low as 1. That's six times stronger than Coke.

2. To carry Coca Cola syrup (the concentrate) the commercial truck must use the Hazardous material place cards reserved for Highly Corrosive materials.
Your point being? The same applies to trucks carrying vinegar concentrate.

3. The distributors of coke have been using it to clean the engines of their trucks for about 20 years! Drink up! No joke. Think what coke and other soft drinks do to your teeth on a daily basis. A tooth will dissolve in a cup of coke in 24-48 hours.
Any carbonated soft drink will help dislodge muck from anything. It's the bubbles what do the job.

Teeth? Nope, sorry. Not enough acid in the drink to do that.
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A rum deal.

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People are funny critters.

I was telling someone last night that I was going to sprinkle some brandy on my Xmas cake and they responded with "With my cake, two slices and you can't stand up".

Really?

Another friend swears that, after two of her sister's rum balls, you will not be able to drive.

Have they thought this through?

You need about 5 standard drinks to reach the legal limit to drive. I have done a few searches of rum ball recipes and the typical level of rum is about 5%. More or less.

Now a standard drink is 30ml for spirits, so to get five drinks worth of rum under your belt you need to eat 3kg (6.6lb) of rum balls in a hour.

And to loosen your belt.

I'm thinking not.

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Halloween & the Chemist

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It's Halloween and I thought a little bit about sulphur would be fitting as sulphur is the basis of brimstone and supposedly the smell of Hades is burning brimstone.

I have never seen as pretty a piece of sulphur as that above, apparently it grew in a volcano. Usually, sulphur is a yellow powder. Dull.

Sulphur is the basis of one of the most common food additives, the preservative sulphur dioxide. Which used to be created by burning sulphur.

Still is in Hell, we are told.

Below is a small video on sulphur put out by the University of Nottingham. Like all good chemistry videos, it has explosions in it.




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Done to a tea.

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Interesting story about tea recently:

A 44-year-old man presented in May, 2001, with muscle cramps. He had recently switched to drinking Earl Grey tea in preference to his regular black tea.

One week after the change, he noticed repeated muscle cramps for some seconds in his right foot. The longer he drank Earl Grey tea, the more intense the muscle cramps became. After 3 weeks, they also occurred in the left foot...

Earl Grey tea is composed of black tea and the essence of bergamot oil, an extract from the rind of bergamot orange (Citrus aurantium ssp bergamia), which has a pleasant, refreshing scent.

(You can skip this paragraph, if you wish) The adverse effects of bergamot oil in this patient are explained by the effect of bergapten as a largely selective axolemmal potassium channel blocker, reducing potassium permeability at the nodes of Ranvier in a time-dependent manner. This may lead to hyperexcitability of the axonal membrane and phasic alterations of potassium currents, causing fasciculations and muscle cramps.

In other words, it disrupts the way chemicals flow through the membrane of the nerve fibres, causing the neurons that connect to the muscles to malfunction.

I should add he was drinking four litres (a gallon, say) a day.

But it plays into my constant refrain: too much of anything is bad for you.

Food-wise, at least.
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