
Jon Baddeley
Specialist Consultant Collectors, Science & Marine
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Specialist Consultant Collectors, Science & Marine

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Invented by Jules Duboscq in 1870, colorimeters are used to determine the concentrations of substances by measuring colour intensities. The Duboscq type of colorimeter works by comparing the colours of two solutions of a coloured substance, a standard with a known concentration, and a sample with an unknown concentration. A clear crystal prism dips into each solution and may be adjusted so that the path lengths of the light through the two solutions can be adjusted. The instrument then takes the light from the two prisms and arranges it to form two halves of an illuminated field in the viewing telescope.
Ph. Pellin became a partner of Jules Duboscq in 1883 and carried on the business after 1886.