A PH. & F. PELLIN, PARIS POLARIMETER. MANY SUBSTANCES HAVE THE PROPERTY, CALLED OPTICAL ACTIVITY, OF ROTATING THE PLANE OF POLARIZATION OF THE LIGHT THAT HAS PASSED THOUGH A SAMPLE. THE AMOUNT OF ROTATION DEPENDS ON THE THICKNESS AND THE CONCENTRATION OF THE SAMPLE AND THEREFORE ONE CAN LEARN VARIOUS PROPERTIES OF A SAMPLE BY MEASUREMENTS OF ITS POLARIZATION. A POLARIMETER ENABLES ONE TO DO THAT BY THE USE OF NICOL PRISMS AT BOTH ENDS. THIS POLARIMETER HAS A GLASS TUBE ABOUT 58 CM LONG THROUGH WHICH THE POLARIZED LIGHT PASSES. AT THE OTHER END IS A POLARIZATION DETECTOR THAT IS ROTATABLE TO MEASURE THE CHANGE IN ANGLE. THE SIGNATURE READS PH & F. PELLIN PARIS. THE HEIGHT IS ADJUSTABLE. THE ANGLE SCALE RANGE IS 100�-0-100� AND IS ABOUT 28 CM IN DIAMETER.
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Van Leest Antiques
Van Leest Antiques, based in Utrecht in the Netherlands, specialises in antique scientific and medical instruments. Their collection covers mainly scientific and medical antique instruments: barometers, globes and planataria, nautical instruments, anatomical models, and pharmacy items. Toon Van Leest travels regularly in Europe and visits trade fairs, auctions, and antique dealers to collect stock and to find pieces to fulfil his clients' unusual requests.
As well as being an avid antique collector and dealer, Toon Van Leest is also a dentist. He believes that antiques are a stable investment, not reliant on trends or fashion, and have truly lasting value. Above all, he says, antiques are timeless and never lose their beauty.