du Noüy surface tension apparatus
Date: circa 1929
Inventory Number: 1998-1-0104
Classification: Surface Tension Apparatus
Maker: Central Scientific Company (1889 - 2000)
Inventor: Pierre Lecomte Du Noüy (1883 - 1947)
User: Department of Physics, Harvard University (founded 1884)
Cultural Region:
Place of Origin:
Dimensions:
instrument: 21.5 × 18.5 × 17.2 cm (8 7/16 × 7 5/16 × 6 3/4 in.)
closed case: 28.8 × 24.6 × 27.4 cm (11 5/16 × 9 11/16 × 10 13/16 in.)
Accessories: wooden case with a metal handle on top, now detached
Bibliography:
Physical Apparatus and Instruments Including Sections on Related Tools and Raw Materials
DescriptionAn apparatus mounted on a three legged stand with a central pillar, fixed with metal brackets 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 label CENTRAL SCIENTIFIC Co.
Inscribedmarked on top: ME17
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.
Curatorial RemarksDate uncertain. It 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 1998-1-0612 but has a different signature and is fixed with brackets, not screws, to the wooden base.
It is also almost identical to 1998-1-0612 but has a different signature and is fixed with brackets, not screws, to the wooden base.
Primary SourcesCentral Scientific Company, Physical Apparatus and Instruments Including Sections on Related Tools and Raw Materials (Boston: Cenco Eastern Division, 1929), 71, No.10400.
ProvenanceFrom the Department of Physics, Jefferson Laboratory, Harvard University.