Experimental chemistry : founded on the work of Dr. Julius Adolph Stöckhardt. A handbook for the study of the science by simple experiments / by C.W. Heaton.

  • Heaton, C. W. (Charles William), -1893.
Date:
1887
Catalogue details

Licence: Public Domain Mark

Credit: Experimental chemistry : founded on the work of Dr. Julius Adolph Stöckhardt. A handbook for the study of the science by simple experiments / by C.W. Heaton. Source: Wellcome Collection.

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    to one ounce of cold water, powdered saltpetre (potassium nitrate), as long as it continues to be dissolved—perhaps about a quarter of an ounce: if more is added than is necessary, it will remain undissolved at the bottom of the vessel. This solution is called a cold saturated solution. If this mixture be boiled, and saltpetre again be added, then about three ounces more will be required to saturate the water. A thermometer held in this boiling saturated solution will indicate about 240° F. (115-5° C.), while simple boiling water indicates only 212° F. (100° C.). All saline solutions boil and freeze with more difficulty than water. All bodies soluble in water behave in a similar manner— that is, they are soluble in it only in definite quantities, and in most cases hot water dissolves more of them than cold. Experiment 6.—If the solution obtained in the last experi- ment be poured into a porcelain dish and be suffered to remain quiet until cold, then the three ounces of saltpetre which were last added separate again, not as a 26 powder, but as regularly formed prisms. These ' prisms are six-sided, and are surmounted by / faces similar to a roof; they are called crystals of 11 saltpetre (Fig. 26.). All crystals are characterized ||j by having planes, edges and angles, constructed, as it were, of simple triangular or quadrangular ‘•AIM pieces, with polished surfaces. This symmetry is found even in the interior of them, as can easily be seen by holding a transparent crystal towards the light, and turning it slowly round; or breaking it, when the fragments will often exhibit the same regular form which characterized the whole crystal, Thus, in inanimate nature, a mysterious power exists, similar to that which compels the bees to construct six-cornered cells, and the potato to produce its five-angled corolla and five stamens, and by which the smallest particles of bodies, called molecules, are forced to arrange themselves in a fixed order, ■assuming a regular shape. But this can in general only be accomplished by a body in its fluid or aeriform state, since free motion of the molecules is essential. Time also is required for this operation; hence crystals are always more regular the more slowly they are formed. Many of E 2