Great Moments in the History of Science

Have you ever wondered what would happen if your dog drank your gin and tonic, then you collected his dog urine and added iodine?

In 1852 in Bristol England a student of Dr. William Herapath did exactly that.

Green crystals grew in the urine.

When Dr. Herapath looked at the crystals under a microscope he noticed that

When the long needle like crystals were parallel they looked green,

wherever the crystals crosssed they looked black.

The crystals were polarizing light.

The quinine from the tonic water combined with the iodine to make quinine sulfate, now called herapathite.

In 1926 Edwin Land used herapathite crystals in a stretched plastic sheet to make a sheet polarizer.

The result were polarized sunglasses!

Wearing polarizing sunglasses reduces glare and allows fishermen to see fish under water.

So the next time you put on your stylish polarized sungkasses think of dogs, gin and tonic, green crystals in dog urine and the nature of scientific curiousity.









Scientific Explorations with Paul Doherty

© 2006

2 December 2006