The principles of chemistry : illustrated by simple experiments / by Julius Adolph Stöckhardt ; translated by C.H. Peirce.

  • Stöckhardt, Julius Adolph, 1809-1886.
Date:
1852
Catalogue details

Licence: Public Domain Mark

Credit: The principles of chemistry : illustrated by simple experiments / by Julius Adolph Stöckhardt ; translated by C.H. Peirce. Source: Wellcome Collection.

Provider: This material has been provided by the National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)

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    paper, and move the vial quickly to and fro on the cord until the latter breaks. Then immediately pour cold water upon the place, and the glass will break as even- ly as if cut. The sharp edges can be removed with a file. In this manner, common vials, and Cologne, and even larger, bottles, may be converted into vessels adapted to chem- ical and other purposes. It is well known that heat is produced by the friction of two bodies upon each other; that by sliding quickly down a line or a pole by the hands, these will be burnt, and that rapid motion will ignite the axles of a carriage, unless they are well greased. Thus, in the above ex- periment, the friction produced great heat in the glass, the string emitted a burnt odor and broke, and great expansion of the glass was produced. When the outer surface was suddenly cooled by the cold water, the expanded particles at once contracted, and more rapidly in the external particles than in those of the inner surface, causing the fracture of the glass; and the more easily the greater its thickness. If the tempera- ture had been slowly reduced, it would not have broken. Thus, it is obvious, (a,) that glass and porcelain ves- sels intended for sustaining high temperatures, such as flasks, alembics, retorts, capsules, &c, should be thin, particularly at the bottom; and (b) that, when used, they should always be gradually heated and cooled. The above method of heating glass by a cord fur- nishes the apothecary with a simple expedient for re- moving stoppers which are too firmly fixed in the bot- tles to be taken out by turning or tapping them. 3*