Procedure - Hydrometer

If large amounts of juice are available, the use of a calibrated hydrometer provides accurate readings quickly and inexpensively. Calibrate the hydrometer in terms of percentage sucrose using watery sucrose standard solutions at 20 °C. Then fill a graduated cylinder with 200 ml of juice at 20 °C, insert the hydrometer and read the value as °Brix, which is equivalent to percentage of soluble solids (Kramer 1973). 

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Bromine vapor can be analy2ed by the same procedure. The specific gravity of bromine is deterrnined by hydrometer (54). 

Test Methods and Procedures 4.3.1 Ethyl Alcohol Content. Determine specific gravity at 15.6/l5.6uC (60/60°F) by means of a calibrated hydrometer, pycnometer or other... 

Procedure Cool to 20° the sample collected in an 8 oz glass-stoppered bottle and fill a hydrometer jar to about %. Insert hydrometer of range 1.0-1.2 and take reading at 20°. Det approx concn from tables, density vs concentration, such as... 

Bearing in mind, from the discussion above, that °Brix really only allows estimation of relative water content in a series of related systems, this measure is used sufficiently frequently to require that the procedures be outlined. The sections below describe the use of the refrac-tometer and the hydrometer for determining water concentration. These instruments are readily available from a number of sources including Brannan and ERTCO Precision (for... 

For accurate work it is necessary to take into account certain correction factors, namely the meniscus correction and the change in suspended material, it is necessary to make readings at the top of the meniscus. Hence, there must be added to the latter a small quantity to correct for the procedure. In the case of water suspensions this correction is about 0.0003, and this figure is generally used. 

Schweyer (1942) compared various methods of particle-size measurement (except centrifuging). He found excellent agreement between pipette and hydrometer methods. He considers the former the best method for determining the particle-m/.c distribution of sub-sieve material by sedimentation, and prefers the hydrometer as a rapid control procedure. 

The changes in density of a settling suspension may be followed with a hydrometer, a method widely used in soil science and in the ceramic industry. A suspension of known concentration is made up and the hydrometer inserted. Some operators leave the hydrometer in the suspension throughout the analysis and some remove it after each reading and replace it slowly before the next. Objections can be raised to either procedure since, in the former, particles settle on the hydrometer causing it to sink to a lower level than it would otherwise sink whereas, in the latter. 

Procedure Fill a test tube two-thirds with saturated sodium chloride and measure the density with hydrometer. Add a spoon of sodium chloride, stir and measure the density again. Add several spoons of the salt to the solution, stir the solution and repeat the density measurement. 

Demonstrate the correct battery charging procedures. You may also want to demonstrate how to use a hydrometer to measure the strength of the battery acid. 

The meaning of the term extract has been debated since 1890. While it obviously means the nonvolatile soluble solids, it is difficult to specify analytically. Godet (1949) and Jaulmes (1951) have summarized the arguments and clarified the issue. At present extract is usually determined by formula based on the specific gravity, by evaporation, or by hydrometer readings on the dealcoholized wine. None of the procedures is entirely satisfactory. 

When using the hydrometer to follow density shifts within a settling suspension one can follow special procedures. In the first method the hydrometer is placed in the suspension and readings of the depth of immersion taken at a series of times. In the alternate procedure, the hydrometer is placed in the suspension prior to each measurement and then withdrawn immediately. 

The alternative experimental procedure of withdrawing the hydrometer between readings over a period of time gives rise to two types of error. When the hydrometer is inserted into the suspension, it displaces and generally disturbs the suspension as it sinks through it. The effect of this disturbance is difficult to estimate, and the cumulative result of a series of insertions and withdrawals can be measured only empirically. Factors that influence the magnitude of the error caused by this disturbance of the suspension are 1) the ratios of the bulb dimensions to those of the sedimentation vessel and 2) the depth to which the hydrometer sinks. 

When gravities have been observed on opaque liquids using the procedure given in 8.6, subtra9t the correction from the hydrometer reading observed. 

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