• Do not allow chemicals to come into contact with the eyes or mouth.
• Keep young children, animals and those not wearing eye protection away from the experimental area.
• Store this experimental set out of reach of children under 12 years of age.
• Clean all equipment after use.
• Make sure that all containers are fully closed and properly stored after use.
• Ensure that all empty containers are disposed of properly.
• Do not use any equipment which has not been supplied with the set or recommended in the instructions for use.
• Do not replace foodstuffs in original container. Dispose of immediately.

• In case of eye contact: Wash out eye with plenty of water, holding eye open if necessary. Seek immediate medical advice.
• If swallowed: Wash out mouth with water, drink some fresh water. Do not induce vomiting. Seek immediate medical advice.
• In case of inhalation: Remove person to fresh air.
• In case of skin contact and burns: Wash affected area with plenty of water for at least 10 minutes.
• In case of doubt, seek medical advice without delay. Take the chemical and its container with you.
• In case of injury always seek medical advice.

• The incorrect use of chemicals can cause injury and damage to health. Only carry out those experiments which are listed in the instructions.
• This experimental set is for use only by children over 12 years.
• Because children’s abilities vary so much, even within age groups, supervising adults should exercise discretion as to which experiments are suitable and safe for them. The instructions should enable supervisors to assess any experiment to establish its suitability for a particular child.
• The supervising adult should discuss the warnings and safety information with the child or children before commencing the experiments. Particular attention should be paid to the safe handling of acids, alkalis and flammable liquids.
• The area surrounding the experiment should be kept clear of any obstructions and away from the storage of food. It should be well lit and ventilated and close to a water supply. A solid table with a heat resistant top should be provided
• Substances in non-reclosable packaging should be used up (completely) during the course of one experiment, i.e. after opening the package.

The outcome of this experiment depends on precisely following the instructions. Let’s repeat the experiment using the same nail and carefully following all the directions.

• The spacing between the tubes should be about 2 mm.

A smaller gap will obstruct the solution’s access to the iron, and the nail won’t break because its core will hardly dissolve. On the other hand, if the gap is too large (greater than 2 mm), the reaction will take place on the nail’s surface instead of concentrating inside the nail. Picture what would happen if a beaver crunched his teeth into the wood all over the tree trunk instead of concentrating on grinding away at one spot. You may agree that in such a case breaking the tree — like the nail — would take way too much time.

• The nail with tubes should be connected to the red wire of the battery holder.

If you reverse the connections, the reaction will “switch” to the bare nail. We won’t succeed in breaking this one because it will dissolve evenly over its entire surface, not in one concentrated spot.

• The crocodile clip should be connected to the head of the nail with tubes.

Otherwise, with no contact between them, our electric circuit will remain open, and the reaction won’t happen.

• The crocodile clips must not touch.

If they touch, the system may short-circuit, overheating and damaging the batteries. They may even leak! This could be unsafe, and will certainly hinder your experiment. Last but not least, check that you inserted the batteries correctly. If the polarity is correct, but the experiment still doesn’t work, try replacing the batteries with new ones.