Exhibition Images

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Dr. J. J. Woodward's Microscope, Light Grand American Microscope, Philadelphia; Manufacturer: Joseph Zentmayer, 1864
Guinea pig blood crystals, 1871
Baboon blood crystals, 1871
Woodward's photomicrography apparatus, Drawing, 1867
Photomicrograph of left posterior stigma of maggot, 1935
Photomicrograph of mandibular sclerite of maggot, 1935
Spectroscope, about 1920
Chart showing the spectra of different types of blood samples, 1894
Beckman DU Spectrophotometer, about 1950
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Beckman DU spectrophotometer, about 1950
Image 27 of 30

Laboratory Views

Beckman DU spectrophotometer, about 1950
The DU spectrophotometer measures the amount of ultraviolet light absorbed by a substance. Developed by Arnold Beckman at National Technical Laboratories to measure the amount of vitamin A in food, it came to be widely used to identify and measure a variety of substances. The DU spectrophotometer was one of several revolutionary devices invented by Beckman: the first "black boxes" in the chemical laboratory. It revolutionized laboratory work by replacing labor-intensive and bulky (and openly visible) chemical procedures with a simple, boxed electronic instrument in which only input and output could be seen.
DeWitt Stetten, Jr., Museum of Medical Research, National Institutes of Health