ASTM D1747 Standard Test Method for Refractive Index of Viscous Materials
1. Scope
1.1 This test method covers the measurement of refractive indexes, accurate to two units in the fourth decimal place, of transparent and light-colored viscous hydrocarbon liquids and melted solids which have refractive indexes in the range between 1.33 and 1.60, and at temperatures from 80 to 100°C. Temperatures lower than 80°C can be used provided that the melting point of the sample is at least 10°C below the test temperature.
1.2 This test method is not applicable, within the accuracy stated, to liquids having colors darker than ASTM Color No. 4 ASTM color as determined by Test Method D1500, to liquids which smoke or vaporize readily at the test temperature, or to solids melting within 10°C of the test temperature.
NOTE 1 - The instrument can be successfully used for refractive indices above 1.60; but since certified liquid standards for ranges above 1.60 are not yet available, the accuracy of measurement under these conditions has not been evaluated.
1.3 The values stated in SI units are to be regarded as standard. The values stated in inch-pound units are for information only.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazards, see Note 4, Note 5, and Note 6.
2. Referenced Documents
2.1 ASTM Standards:
D362 Specification for Industrial Grade Toluene
D841 Specification for Nitration Grade Toluene
D1218 Test Method for Refractive Index and Refractive Dispersion of Hydrocarbon Liquids
D1500 Test Method for ASTM Color of Petroleum Products (ASTM Color Scale)
E 1 Specification for ASTM Thermometers
3. Terminology
3.1 Definition:
3.1.1 refractive index - the ratio of the velocity of light (of specified wavelength) in air, to its velocity in the substance under examination. The relative index of refraction is defined as the sine of the angle of incidence divided by the sine of the angle of refraction, as light passes from air into the substance. If absolute refractive index (that is, referred to vacuum) is desired, this value should be multiplied by the factor 1.00027, the absolute refractive index of air. The numerical value of refractive index of liquids varies inversely with both wavelength and temperature.
