- This instrument marked "Franz Schmidt & Haensch, Berlin, S." and "No. 9338" is a half shadow polariscope equipped with a Lippich polarizer with lever adjustment. It has a graduated circle read by two verniers, each with a magnifier and an illuminating mirror. It can hold observation tubes up to 220 mm in length. According to Eimer & Amend, the New York firm that imported Schmidt & Haensch instruments into the United States, this model was accurate to 0.05 degrees, and was used "in chemical laboratories and universities for general and research investigations." This example belonged to Robert Meyer Leonard, a pharmacologist who taught at George Washington University and then served as a health science administrator at the National Institutes of Health.
- With any half-shadow polariscope, the observer equalizes the darkness (rather than the color) of the various parts of the image. The Lippich polarizer produces a tri-part field of view. Set at zero, the three segments appear the same, but in other positions the center segment is shaded while the outer two remain equally illuminated. Ferdinand Lippich, a professor of mathematical physics at the German University in Prague, described this form in 1894.
- Eimer & Amend introduced the new Schmidt & Haensch half shadow polariscopes with triple field of view in 1895, noting that they "have received the unanimous approval of prominent sugar chemists abroad and such an authority as Prof. Landolt especially, is of the opinion that they will supersede all other Polariscopes, on account of their extreme sensitiveness." George Stade, a chemist in Berlin, was equally effusive about "Lippich’s Three Division Observation Instrument" with three Glan’s prisms. In his words, it "enables almost everybody to make, without difficulty, an exact reading of 0.1 deg," combines "all the advantages of the half shadow instruments," and "is, no doubt, the most perfect polariscope in the market, and with regard to sensitiveness and precision has no equal up to now."
- Ref: F. Lippich, “Ueber eine verbesserungen Halbschatten-Polarisationsapparaten,” Zeitschrift für Instrumentendekunde 14 (1894): 326-327 and 420.
- Eimer & Amend, Illustrated Catalogue with Prices Current of Chemical & Physical Apparatus (New York, 1895), p. 392.
- Geo. Stade, “Modern Polariscopes,” International Sugar Journal 1 (1899): 65-72.
- Baird & Tatlock, Price List of Chemical and Bacteriological Apparatus, Chemicals, and Reagents (London, 1914), p. 1059.
- Currently not on view
- Object Name
- Franz Schmidt & Haensch
- place made
- Germany: Berlin, Berlin
- overall: 45.7 cm x 27.9 cm x 58.4 cm; 18 in x 10 31/32 in x 23 in
- overall: 18 in x 11 in x 22 7/8 in; 45.72 cm x 27.94 cm x 58.1025 cm
- ID Number
- catalog number
- accession number
- Data Source
- National Museum of American History
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