Hydrometers have been used for testing the specific gravity of many liquids. This selection includes an oiliometer, the hydrometer on the left of the picture which was made for oil density experiments, by Dring and Fage, Tooley Street, London, around 1870. It is made of German silver with an ivory scale and glas test jar. Bartholomew Sikes' hydrometer is in the centre of the picture. This was accepted by the British Government for revenue purposes in measuring the strength of alcoholic spirits in 1816. The one shown here is a portable gilt Sike's hydrometer made by Dring and Fage about 1873. The set of four glas hydrometers weighted with mercury was made around 1830 by Dring and Fage.
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