A hydrometer is a device for measuring the density of liquids and solids, the principle of which is based on the Law of Archimedes [1] . Hypathy is believed to have invented the hydrometer.
Usually it is a glass tube, the lower part of which during calibration is filled with shot or mercury to achieve the required mass. In the upper, narrow part is a scale that is calibrated in the values of the density of the solution or the concentration of the dissolved substance. The density of the solution is equal to the ratio of the mass of the hydrometer to the volume by which it is immersed in the liquid. Accordingly, there are distinguished hydrometers of constant volume and hydrometers of constant mass [1] .
- To measure the density of a liquid with a constant mass hydrometer, a dry and clean hydrometer is placed in a vessel with this liquid so that it floats freely in it. The density values are read on the scale of the hydrometer, on the lower edge of the meniscus.
- To measure a constant volume with a hydrometer, its mass is changed, reaching its immersion to a certain mark. Density is determined by the mass of the cargo (for example, a weight) and the volume of displaced fluid.
For practical use, the hydrometer is graduated in the concentration of the dissolved substance, for example:
- Alcohol meter - in percent alcohol to measure the strength of the drink;
- Lactometer - in percentage of fat to determine the quality of milk ;
- Saline tester - for measuring salinity of a solution ;
- Sugar meter - in determining the concentration of dissolved sugar ;
Since the density of liquids is highly dependent on temperature, concentration measurements should be carried out at a strictly defined temperature, for which the hydrometer is sometimes equipped with a thermometer .
The following types of hydrometers are distinguished:
- general-purpose hydrometer AON-1, AON-2, AON-3, AON-4, AON-5;
- hydrometer for milk AM, AMT;
- hydrometer for oil products AN, ANT-1, ANT-2;
- hydrometer for urine AU;
- hydrometer for alcohol ASP-1, ASP-2, ASP-3, ASP-T;
- hydrometer for electrolyte AE-1, AE-2, AE-3;
- hydrometer for soil AG;
- hydrometer for sugar AC-2, AC-3, AST-1, AST-2;
- hydrometer for acids AK-1, AK-2;
- hydrometer-hydrometer with AEG thermometer.
Notes
- ↑ 1 2 Physical Encyclopedic Dictionary / Ch. ed. A.M. Prokhorov. Ed. count D.M. Alekseev, A.M. Bonch-Bruevich, A.S. Borovik, etc. - M .: Sov. Encyclopedia, 1983. - S. 32-33. - 982 s. - 100,000 copies.
Links
- Hydrometer // Brockhaus and Efron Encyclopedic Dictionary : in 86 volumes (82 volumes and 4 additional). - SPb. , 1890-1907.