Ask Mr Brain...all will be explained

PUBLISHED : Wednesday, 08 September, 1999, 12:00am
UPDATED : Wednesday, 08 September, 1999, 12:00am

Why is snow white? Water is colourless and so is ice. Snow is made up of tiny ice crystals. When we make iced drinks and grind a big piece of ice into flakes, we will find that the flakes appear to be white. What turns snowflakes white is the reflection of light. When a piece of ice is intact, the surface is smooth and light can pass through easily. When it is broken up, the surface becomes irregular and light will be reflected in many directions and the ice will appear to be white.

The smaller the crystal, the more light it will reflect. Snowflakes are irregular and have many edges, re flecting a large amount of light. That's why they look white.

Where do polar bears live? Polar bears can be found throughout the Arctic and northern Canada especially around southeast Baffin Island, Lancaster Sound and the Barrow Strait. They are excellent swimmers well adapted to the Arctic marine environment with a thick layer of body fat and dense fur with hollow hair for insulation. They spend most of their time at sea and on ice floes where they can find their main staple food - seals. Being solitary animals, they travel alone and only get together to mate.

How do anaesthetics work? ALICE CHOW Sacred Heart Canossian College Anaesthetics are substances which block the nerves from sending pain messages along the nervous system (local or regional anaesthetics) or which render the patient unconscious (general anaesthetic) so that the brain is unable to perceive pain signals.

The discovery of anaesthetics was one of the most important dis coveries in Western medicine - pain-free surgery. Up until 150 years ago, surgery was regarded as a last resort since methods of beating pain were crude and ineffective. Opium, alcohol, hypnosis and even simply knocking the patient unconscious were all used.

In Britain, experiments had shown that breathing nitrous oxide ('laughing gas') made people happy and insensitive to pain. However, it was at first regarded as a music hall amusement rather than a discovery with medical possibilities.

In the United States, experiments were made using ether and on March 30, 1842, Dr Crawford Long of Georgia made the first operation using an anaesthetic - ether.

However, ether was not widely used until Dr William Morton gave his famous demonstration using ether at Massachusetts General Hospital in Boston. Patient Gilbert Abbott had a tumour removed from his jaw. He came round after the surgery to inform the sceptical audience that he had felt no pain. The surgeon, John Warren, ushered in a new era of medicine with the words: 'Gentlemen, this is no humbug.' Since then, more effective and safer anaesthetics have been developed. For more information on the history of anaesthetics, try the Massachusetts General Hospital site on ether at http://brain.mgh.harvard. edu:100/History/ether1.htm or the Virtual Museum of Anaesthesiology at aha/vma