orr_1936

W. J. C. Orr, Trans. Faraday Soc. 32, 1556 (1936)

Source record · Catalogue · Review register

DOI: 10.1039/tf9363201556

Source kind: measurement

Recorded technique: Rayleigh gas interferometer (75 cm gas tubes) with electrolytic H2 in one tube and D2 (from 99.1 % D2O, final D concentration 99.9 +- 0.2 %) in the other, both streaming at room temperature and at equal pressure (checked by a differential manometer), vented to the atmosphere; fringe shift read on the compensator drum (35.0 divisions), the drum calibrated with the 5462 A mercury line (14.25 divisions per fringe).

Materials in structured entries: D2

Dataset quantities: refractivity

Contents: 1 dataset; 0 formulas.

Curation notes

The measurement is the difference n_H2 - n_D2 = 35.0/14.25 x 5462/75 x 1e-8 = (179 +- 2) x 10^-8 at 5462 A (p. 3), deuterium having the smaller index. It is made at room temperature and near atmospheric pressure, neither stated. The paper then subtracts it, unscaled, from the International Critical Tables value for H2, 1.00013966 at 5462 A, 273 K and 760 mm, and gives n_D2 = 1.0001378(7) ‘under the same conditions’ (p. 3). Two caveats make that absolute value a check rather than a datum: (1) it inherits the ICT hydrogen value, which Peck & Huang (1977) show to be high by about 0.25 % (their absolute H2 refractivity at 546.2 nm is 139.304e-6 at 0 C and 760 Torr against ICT’s 139.66e-6); (2) the difference was measured at room density and not scaled to 0 C (at about 290 K it would be some 6 % larger at 0 C, i.e. about 190e-8; the paper does not give the room temperature, so this cannot be done exactly). The independent result is the fractional difference: D2’s refractivity is about 1.3-1.4 % below H2’s at 546 nm. The package has no quantity for a refractivity difference; a refractivity_ratio would need the room-condition H2 refractivity, which is not printed. The raw drum-reading tables (tbl_9411e045eb4e, tbl_aee47e92d4aa, tbl_d00339570e78) are not extracted. The wavelength ‘5462 A’ is the mercury green line’s vacuum wavelength rounded (5460.74 A in air).

Recorded bibliographic identity status: VALIDATED_WITH_WARNINGS. This concerns identification of the source; it does not establish the scientific correctness of its contents.

Datasets

orr_1936/n_D2

{
  "id": "n_D2",
  "material": "D2",
  "table": "text",
  "quantity": "refractivity",
  "scale": 1e-06,
  "abscissa_unit": "angstrom",
  "wavelength_medium": "vacuum",
  "state": "1atm_0C",
  "density": "unknown",
  "use": "check",
  "uncertainty": {
    "column": true,
    "level": "not stated"
  }
}

1 inline points in the source record.

p. 3: n_D2 = 1.0001378(7) at 273 K and 760 mm, printed with its last digit in parentheses (an uncertain digit), entered as (n - 1) x 1e6 = 137.87. It is ICT’s H2 value 1.00013966 minus the measured (179 +- 2)e-8, so the sigma (0.02e-6) is the difference’s alone; the ICT value’s own error (about +0.25 %, see the source notes) is not included. Not fitted: see the source notes.

Formulas

No formulas are recorded.

Corrections

No dataset errata are recorded in this source record.

Formula corrections, where recorded, appear with their formulas above. Curation notes may also discuss corrections or unresolved interpretation. Consult the review register for the checks and decisions.