Dental chemistry and metallurgy.

  • Mitchell, Clifford, 1854-1939.
Date:
1890
Catalogue details

Licence: Public Domain Mark

Credit: Dental chemistry and metallurgy. Source: Wellcome Collection.

Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.

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    taining- powder full of water and weigh again. Subtract weight of flask filled with water from weight of flask filled with powder and water mixed. The difference will be the loss of weight ofihe powder. Divide the weight of the powder in air by the loss of weight in water, and the quotient will be the specific gravity of the powder. {e) To find the sp. gr. of liquids a special flask, called a picnometer or sp. gr. flask, is used which contains a certain weight of water when filled. This weight is marked on the flask. To ascertain the sp. gr. of a liquid by means of its use, weigh it, fill it with the liquid and weigh it, subtract weight of flask, and divide difference by number marked on the flask. The quotient will be the sp. gr. of the liquid. The temperature of the liquid should be that marked on the flask. Instruments called hydrometers'^' are also used for finding the sp. gr. of liquids, and are long, narrow, glass or metal tubes provided with a bulb near the bottom filled with air, and a smaller one below it filled with mercury. To find the sp. gr. it is merely necessary to drop the hydrometer into the liquid and read off the number on the scale at the surface of the liquid. *Hydrometers should be those carefully standardized to a certain temperature, as 77 F., and used in liquids warmed or cooled to that temperature.