Dr William Bird Herapath FRS FRSE FRCS (28 February 1820 – 12 October 1868) was an English surgeon and chemist known for his discovery of Herapathite.
[3] In 1852 one of his pupils found that adding iodine to the urine of a dog that had been fed quinine produced unusual green crystals.
Herapath noticed while studying the crystals under a microscope that they appeared to polarize light and patented the discovery for optical use as Herapathite.
He went on to develop new analytical techniques for the detection and analysis of alkaloid compounds based on the optical and chemical characteristics of their iodo-sulphates.
The embedding of microscopic crystals of herapathite in a clear film was later patented by Edwin H. Land as a polarizing filter, under the name of Polaroid.