Lime water is the common name for saturated calcium hydroxide solution. It is sparsely soluble. Its chemical formula is Ca(OH)₂. Since calcium hydroxide is only sparsely soluble, i.e. ca. 1.5g per liter at 25°C^[1], there is no visible distinction to clear water. Attentive observers would notice a slightly earthy smell. It is clearly distinguishable by the alkaline taste of the calcium hydroxide. The term is based on the mineral sense of lime, rather than the fruit sense of lime. When exposed with carbon dioxide, lime water turns into a milky solution.

While lime water is a clear solution, milk of lime on the other hand is a suspension of calcium hydroxide particles in water. These particles give it the milky aspect. It is commonly produced by reacting quicklime (calcium oxide) with an excess of water - usually 4 to 8 times the amount of water to the amount of quicklime. Reacting water with quicklime is sometimes referred to as "slaking" the lime. The calcium oxide will convert to the hydroxide according to the following reaction scheme:

CaO + H₂O → Ca(OH)₂

This reaction is strongly exothermic and will generate enough heat to bring the suspension to a scalding temperature. At a ratio of 2 parts water to 1 part lime (by weight), the generated heat is sufficient to bring the suspension, i.e. the water in it, to boil. Milk of lime is an alkaline with a pH of 12.3. It is commonly used in the chemical industry and as a neutralizing agent in municipal waste water treatment. While it has a multitude of other uses, it is best known in its (historical) use as a paint: lime wash or whitewash.

abstracted from: http://en.wikipedia.org/wiki/Lime_water

The claims that have become popular on a number of examination courses around the world are that:

1. Wasp sting venom is alkaline and so its effects can be neutralised with vinegar or acid and this neutralisationthen reduces the pain.

2. Bee sting venom is acidic and so its effects can be neutralised with bicarbonate of soda or alkali and this reaction reduces the pain.

Are either of these statements true?

The facts are that:

• Bee venom contains formic acid (also known as methanoic acid) but this is not the single active ingredient that causes the pain from a bee sting
• Wasp stings are alkali but once again the venom has so many active ingredients that it is very unlikely that it is the alkali alone that is the single active ingredient that causes the pain

Neutralising a sting with either vinegar or bicarbonate of soda is unlikely to be effective or even practically possible because:

1) The venom from wasps and bees is injected under the skin and after a few minutes spreads deep into the tissues. Sloshing unknown strength vinegar or bicarbonate of soda onto the skin surface is unlikely to even get near the venom so no "neutralisation" is likely to take place anyway.

2) A wasp or bee sting is between 5 and 50 micrograms of fluid - this is a tiny amount of fluid - a little pinhead or the size of this full stop . - and it is hard to believe how pouring comparatively huge volumes of unknown strength vinegar or rubbing lumps of bicarbonate of soda near the venom of unknown ph is going to produce a perfectly neutral ph which neutralises the sting and stops it hurting.

So, I confidently state that vinegar and bicarbonate of soda (or at least their acidity or alkalinity) have no real physical effect on how much a sting hurts or continues hurting.

I would also add that

• rubbing a wound distracts the mind from the immediate pain and
• rubbing a wound with anything safe promotes the release of endorphins which may reduce the pain,
• if you believe something is going to work, then it often will because the mind can play curious tricks!

There are plenty of very subjective but genuine and honest claims for the following treatments:

• applying meat tenderizer,
• applying toothpaste,
• applying tobacco,
• applying papain (latex from the papaya tree)
• applying mashed up root of pineapple
• applying chilli paste
• applying Mum roll on deoderant,
• applying mint leaves
• applying four types of grass
• applying clay paste, and
• applying a copper coin
• squeezing the sting with a clothes peg for 20 minutes
• applying a paste of green clay
• applying hot water to coagulate the venom
• applying lavendar oil
• applying crushed bracken fern
• applying Sudocrem to sting site
• applying a slice of raw onion

Each of these remedies I am advised have a hugely beneficial effect on insect sting pain.