du Noüy surface tension apparatus
Datecirca 1940
Inventory Number1998-1-0612
ClassificationSurface Tension Apparatus
Subject
Maker
Central Scientific Company
1889 - 2000
Inventor
Pierre Lecomte Du Noüy
1883 - 1947
Cultural Region
Place of Origin
Dimensionsinstrument: 22 × 18.3 × 16.3 cm (8 11/16 × 7 3/16 × 6 7/16 in.)
closed case: 31.3 × 24.8 × 27.8 cm (12 5/16 × 9 3/4 × 10 15/16 in.)
closed case: 31.3 × 24.8 × 27.8 cm (12 5/16 × 9 3/4 × 10 15/16 in.)
Material
Accessoriesa wooden case with a metal handle on top
Bibliography
DescriptionAn apparatus mounted on a three legged metal stand with a central pillar, fixed by screws to a wooden base.
The apparatus consists of a flat, disk-shaped platform held by a metal arm that is attached to the end of one of the three legs. The platform's height can be adjusted roughly from the base of the arm that holds it and very precisely with a screw that is below the base of the platform.
Above the platform hangs a delicate platinum ring oriented horizontally, held by a vertical platinum stirrup hanging from a horizontal aluminum arm. This arm is clamped to a metal wire (see below) at its other end after passing over a small platform held by a metal arm coming from the central pillar of the stand.
The central pillar holds a long, rectangular metal platform above which is the metal wire (a torsion wire) tensioned by knobs at both ends of the rectangular platform which can be turned to twist the metal wire. One of the knobs is at the center of a large, circular dial graduated in degrees, with a fat metal arm indicating the degrees that the metal wire is currently twisted.
The apparatus consists of a flat, disk-shaped platform held by a metal arm that is attached to the end of one of the three legs. The platform's height can be adjusted roughly from the base of the arm that holds it and very precisely with a screw that is below the base of the platform.
Above the platform hangs a delicate platinum ring oriented horizontally, held by a vertical platinum stirrup hanging from a horizontal aluminum arm. This arm is clamped to a metal wire (see below) at its other end after passing over a small platform held by a metal arm coming from the central pillar of the stand.
The central pillar holds a long, rectangular metal platform above which is the metal wire (a torsion wire) tensioned by knobs at both ends of the rectangular platform which can be turned to twist the metal wire. One of the knobs is at the center of a large, circular dial graduated in degrees, with a fat metal arm indicating the degrees that the metal wire is currently twisted.
Signedon dial: TRADE MARK / CENCO / REG.US.PAT.OFF.
Inscribedon label: From A-B Set Up.
Curatorial RemarksDate uncertain. Is almost identical to the one in the 1929 CENCO catalog (see primary sources) except the dial indicator is much thicker, and the platinum stirrup hangs directly from the aluminum arm, without strings.
It is also almost identical to 1998-1-0104 but has a different signature and is fixed with screws, not brackets, to the wooden base.
FunctionThis is an apparatus for measuring the surface tension of liquids. The container with the liquid to be examined would be placed on the platform, the height of which would be adjusted until the platinum ring is submerged in the liquid. The apparatus would then be adjusted such that the aluminum arm was horizontal as the angle in the dial indicated zero.
Once the device was ready, the user would slowly lower the platform by turning the screw below it, until the ring started to emerge from the liquid. At this point, the surface tension would start to act on the ring, pulling on the aluminum arm and lowering it as a result by twisting the wire. The user would turn the knob on the dial changing the torsion angle of the wire until the aluminum arm was restored back to its horizontal position. This process would be repeated carefully several times until the film of liquid pulling on the ring finally snaps. This would give the final reading in degrees. Before its use, the torsion wire would need to be calibrated to find the relationship between torsion angle and balancing force on the aluminum arm, the latter being convertible to surface tension if one knows the dimensions of the metal ring.
Once the device was ready, the user would slowly lower the platform by turning the screw below it, until the ring started to emerge from the liquid. At this point, the surface tension would start to act on the ring, pulling on the aluminum arm and lowering it as a result by twisting the wire. The user would turn the knob on the dial changing the torsion angle of the wire until the aluminum arm was restored back to its horizontal position. This process would be repeated carefully several times until the film of liquid pulling on the ring finally snaps. This would give the final reading in degrees. Before its use, the torsion wire would need to be calibrated to find the relationship between torsion angle and balancing force on the aluminum arm, the latter being convertible to surface tension if one knows the dimensions of the metal ring.
Central Scientific Company
Date: circa 1929
Accessories: wooden case with a metal handle on top, now detached
Object number: 1998-1-0104
Central Scientific Company
Date: circa 1925
Accessories: steel cap; spare torsion wire; glass circular bowls (2); platinum ring seems to be missing; case
Object number: 1995-1-0011
Carl Zeiss Jena
Date: circa 1926
Accessories: wooden box with two hook-and-eye latches to fasten front opening; in instrument file: instruction book (photocopy); Geissler tube labeled "H2"; carboard tube containing German thermometer C in stainless steel holder that screws into instrument; glass bottle with cork stopper labeled "Monobromnaphthalin, Germany nD=1 658"; small round cardboard box labeled "For Pulfrich Refractometer" containing one tubulure
Object number: 1996-1-0229
Harold C. Ernst
Date: 1900-1930
Accessories: leveling screw
Object number: 1996-1-0178
R. & J. Beck
Date: 1876
Accessories: oculars (2) in microscope; Darker's selenite retarding filters (3); wheel diaphragm; mechanical rotary stage; stage slider. Other accessories are in the case (1122b), including monocular draw tube; oculars (3); objectives in cans (5); empty can; Lieberkühn; polarizing set; slides; camera lucidas (2); etc.; plus a Beck patent substage condenser (1122c); and apertometer (1122d).
Object number: 1122a
French
Date: circa 1850
Accessories: 3 lenses; brass stage plate; case.
Object number: 1990-2-0003
E. Hartnack & A. Prazmowski
Date: circa 1870
Accessories: objectives (7): 1, 2, 4, 5, 7, 9,10 in fitted box ; eyepieces (4): 1, 4, 5, 6; cup diaphragms (4); polarizer set; bull's eye condenser on stand; Oberhaeuser-style camera lucida; tweezers; substage rotating wheel diaphragm attached to holder with blue glass filter; substage glass filter holder with blue glass filter; substage condenser; dual nosepiece, Hartnack 1/100 mm stage micrometer; flat case; key; magnification table; price lists (2).
Object number: 1080