The principles of chemistry : illustrated by simple experiments / by Julius Adolph Stöckhardt ; translated form the 5th German edition by C.H. Peirce.

  • Stöckhardt, Julius Adolph, 1809-1866.
Date:
1851
Catalogue details

Licence: Public Domain Mark

Credit: The principles of chemistry : illustrated by simple experiments / by Julius Adolph Stöckhardt ; translated form the 5th German edition by C.H. Peirce. Source: Wellcome Collection.

    68/710 (page 44)
    like water are called non-conductors of heat. In the former class are included particularly the metals, and in the latter, stone, glass, wood, snow, water, and especial¬ ly cloth, fur, linen, straw, paper, ashes, Ac. The conductors are readily heated, and soon become cold again, as is well known to be the case with iron stoves. A piece of bon feels hotter in the sun and colder in the shade than a piece of wood at the same temperature. The explanation of this delusion of the sense of touch is, that the warm iron conducts the heat more rapidly to the hand, while the cold iron withdraws it more rapidly than the wood is capable of doing. The non-conductors of heat are slowly heated, and also slowly cooled; for this reason, stoves constructed of brick (the Russian stove) and those made of Dutch tiles, a preparation of clay, retain their heat longer than iron stoves. Non-conductors are frequently employed both for preventing the quick heating and the quick cooling of bodies. Vessels of glass and porcelain are placed on sand (a sand-bath) or ashes, to heat them gradually, and thus guard against their breaking. If a hot liquid is to be poured into them, it must be done by small portions at a time, twirling the vessels round for some minutes before adding more. On removing a vessel from the fire, the precaution should be taken never to place it while hot on metal or stone, but always on some non-conductor, such as straw (straw rings), wood, paper, cloth, Ac. ; as they are often cracked by sudden cooling and contraction, which is also frequently caused by a current of cold air. Doors of furnaces, ladles, Ac., are provided with wooden handles to prevent those using them from being burnt. Should a person desire to hold a flask or a test-tube while liquids are boiling in them, he must wrap round