Abbe type refractometer

Refractive Index Measurements. Refractive indices were measured at 23 °C on molded polymer sheets, using an Abbe type refractometer. Suitable contact liquids were employed as required. 

Abbe-Type Refractometer Use an instrument with fourth decimal place accuracy that can be placed in a nearly horizontal position for measurement of the refractive index of solids. An Amici-type compensating prism for achromatiza-tion is necessary unless a sodium vapor lamp is used as a light source. 

The refractive index [n] of an oil with reference to air is the ration of the sine of the angle of incidence to the sine of the angle of refraction of a beam of light passing from air through the oil. It varies with the wavelength of the light used in this measurement. Abbe-type refractometers are widely used for the determination of the refractive index. 

Precautions—In using pure liquids for calibration or checking of calibration of an Abbe-type refractometer, the following precautions should be observed ... 

Rack, vacuum, 4 ft long, 3 ft high A inch rods 3,4 ft rods, 4, 3 ft rods Receiver, udder type Refractometer, Abbe Ring, cork, 250 mL Rings, cork, 50 mL Sacks, paper, to get dry ice in Stopcock, straight, 2 mm Stopper, rubber, 1 hole. No. 3 Stopper, rubber, 1 hole. No. 7 Strip, terminal, 3 port minimum Support rack, stirring motor rack 10/30 Thermometer, 5 cm immersion, -10 to 150 C Towel to crush dry ice in Transformers, variable Traps, vapor... 

In order to determine molecular weight by light scattering, the refractive index Hq of the solvent and the refractive index increment dn/dc) for the solution at a constant temperature must be known. The former is readily measured with a simple laboratory refractometer such as the Abbe type. Determination of dnjdc) of the solution with high accuracy can be achieved by using two types of refractometers divided-cell differential refractometers and interferometers. 

In Abbe s double prism method a thin ho-meotropically oriented nematic film is placed between the hypotenuse faces of two rectangular prisms. Using light polarized parallel and perpendicular to the optical axis, respectively, the principal refractive indices and can be obtained directly from the critical angle of total reflection, provided that the refractive index of the prism is greater than that of the liquid crystal [2, 8-10]. In some cases the director of the nematic phase was oriented uniformly parallel to the prism planes [11-14]. Special variants of the total reflection method have been described [3, 4, 15, 16]. A total reflection refractometer of the Abbe type has also been used to determine n, n and An in the infrared region between 2.5 and 14 p.m [17]. 

Refractometer, precision Abbe-type, having a range in refractive index from 1.30 to 1.63. The prism assembly shall be insulated with cork as necessary to minimize temperature fluctuations during measurement of the refractive index. 

The Abbe-type precision refractometer is no longer available but may be obtainable from instrument exchanges or used equipment suppliers. Other precision refractometers may be suitable, but they have not as yet been tested cooperatively. 

Refractometers. There are several types of refractometers used for determining the refractive indices of liquids. The Abbe refrac-tometer is widely used because it employs only a few drops of the material and requires but a few minutes for the determination. The Fisher refractometer has been introduced recently and is particularly adapted to the student s use. 

Concentration measurements of aqueous solutions of salt, sugar, antifreeze etc. Quality control of a number of industrial processes requires checking the concentration stability of different solutions and water soluble fluids. The off-line use of Abbe refractometers is sometimes an obstacle to real-time process control. Several researchers have tested different types of LPGs for the measurement of concentrations of aqueous solutions of sugar, salts, and antifreeze. Falciai et al. [16] used a UV written LPG (X = 1,530 nm, A - 400 pm) to measure concentrations of aqueous solutions of sodium chloride (NaCl) and calcium chloride (CaCl2) having refractive indices in the 1.32-1.42 range. In a later paper, Falciai et al. [17] also measured... 

The densities of pure components and their nrixtures were measured with an Anton Paar DMA 55 densimeter, and the refractive indices with an Abbe refractometer Type 3T., with accuracies of 0.01 kg my3, and 0.0002, respectively. Each apparatus was matched to a Julabo circrrlator with proportional temperature control aird an autonratic drift correction system that kept the samples at desired temperature usually 298.15 K with accuracy of 0.01 K. The densimeter was calibrated periodically with distilled water and dry air. 

The aniline p.a. (Merck) was fresh distilled, and the solvents were purified by known methods [58]. The refractive indices n, were determined with an Abbe refractometer, of the G type, for the yellow sodium light. The dielectric constants, D, were evaluated with an Oehme apparatus of 600 RL Type, and together with the n s and the boiling points, b.p. as purity criteria, are given in Table 1. The temperature was maintained constant with an Ultrathermostat U 10, at 20- 0.1 . The spectra were recorded with a S RECORD UV-VIS spectrophotometer, Carl Zeiss, 3ena, having an accuracy... 

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