An important skill for scientists is to be able to investigate claims. This is equally important when you are an adult and you are trying to establish the things manufacturers claim about a product are true.

In this activity you are going to investigate Epsom salts, which are often sold as a cure for stress and sore muscles. They can be bought in chemist shops or pharmacies and are often found in bath salts.

Epsom salts are named after the town of Epsom in Surrey, which has a naturally-occuring, bitter tasting spring, containing a solution of Epsom salts.

The chemical name for the compound that is commonly known as Epsom salt is magnesium sulphate.

Q: Which three elements are present in magnesium sulphate?

Examine a sample of epsom salts using a hand lens or magnifying glass. How would you describe it?

Magnesium is an essential element in the human body.

Q: Why our bodies need magnesium.

Some materials are soluble in water and others aren’t. Try dissolving a spoonful of Epsom salts in one third of a cup of water. Stir well; is it soluble?

Now it’s time to try and grow crystals.

  1. Measure out 200ml of Epsom salts into a beaker and add an equal volume of hot, but not boiling, water.
  2. Stir well to completely dissolve the solid, then drop in a few grains of clean sand to give the crystals something to grow on.
  3. For best results, the beaker should go in a freezer for 10 minutes and then into a fridge, but if you can’t use a freezer, it should still work.
  4. Keep in the fridge overnight or (preferably) longer.
  5. Pour off the water and examine with a hand lens/ magnifying glass.

Although magnesium is essential for the body, there is no conclusive evidence to suggest it can be absorbed through the skin. How would you respond to an advert claiming that bathing in Epsom salts is a good way of avoiding magnesium deficiency?

A common use for Epsom salts is dissolving them in water to create a relaxing bath. See if you can get members of your family to volunteer to try this out and report back on whether it works for them. Do they experience any benefits and, if so, what?

Don’t forget to send us a picture of the crystals that you grew, along with your observations and/or results of any of the other parts of your investigation and the answers to the two questions above, and you could win a prize!

If you want to take part in tomorrow’s activity, you will need a Jenga set (or similar) and some stickers.

Until next time, Keep calm and apply some Science!

This activity has been taken from the downloadable resources on