Chemical Recreations: A Compendium of Experimental Chemistry, 第 1 部分

R. Griffin and Company, 1838 - 326页

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第94页 - ... till it crystallizes on cooling. Alter the position of every crystal, once at least every day, with a glass rod, that all the faces may be alternately exposed to the action of the liquid ; for the face on which the crystal rests never receives any increase. By this process the crystals gradually increase in size.
第107页 - Its smallncss, which rentiers it suitable to the pocket, is no inconsiderable recommendation. The most expensive materials, and the minutest specimens of bodies, may be used in these experiments ; and the whole process, instead of being carried on in an opaque vessel, is under the eye of the observer from beginning to end. It is true, that very little can be determined in this way concerning the quantities of products ; but, in most cases, a knowledge...
第211页 - Suppose this operation to be performed under one of the jars which are filled with water, the air will ascend as before ; but, instead of escaping, it will be detained in the upper part of the jar.
第xix页 - ... such experiments as verify its fundamental truths. The hearing of lectures, and the reading of books, will never benefit him who attends to nothing else ; for Chemistry can only be studied to advantage practically. One experiment, well conducted, and carefully observed by the student, from first to last, will afford more knowledge than the mere perusal of a whole volume. DIFFERENT CLASSES OF EXPERIMENTS. — Chemical experiments may be divided, for convenience, into three sorts ; namely, Determinative,...
第115页 - ... the mouth and the passage of the nostrils ; by which means the operator is at liberty to breathe through the nostrils, at the same time that by the muscles of the lips he forces a continual stream of air from the anterior part of the mouth through the blowpipe. When the mouth begins to be empty, it is replenished by the lungs in an instant, while the tongue is withdrawn from the roof of the mouth, and replaced again in the same manner as in pronouncing the monosyllable tut.
第102页 - Alkaline fluxes are either the crude flux, the white flux, or the black flux. Crude flux is a mixture of nitre and tartar, which is put into the crucible with the mineral intended to be fused. The detonation of the nitre with the inflammable matter of the tartar is of service in some operations, though generally it is attended with inconvenience, on account of the swelling of the materials, which may throw them out of the vessel.
第112页 - The stream of air must be blown along this horizontal part, as near as may be without striking the wick. If the flame be ragged and irregular, it is a proof, that the hole is not round or smooth; and if the flame have a cavity through it, the aperture of the pipe is too large. When the hole is of a proper figure and duly proportioned, the flame consists of a neat luminous blue cone, surrounded by another flame of a more faint and indistinct appearance. The strongest heat is at the point of the inner...
第261页 - For general and ordinary chemical purposes," says Dr Henry, " and even for the prosecution of new and important inquiries, very simple means are sufficient: some of the most interesting facts of the science may be exhibited and ascertained with the aid merely of Florence flasks, of common phials, and of wine glasses. In converting these to the purposes of apparatus, a considerable saving of expense will accrue to the experimentalist; and he will avoid...
第274页 - This is formed by beating perfectly dry and finely-sifted tobacco-pipe clay, with painters' drying oil, in a mortar, to such a consistence that it may be moulded by the hand. To use it, it is rolled into cylinders of a convenient size, which are applied, by flattening them, to the joinings of the vessels, which must be quite dry, as the least moisture prevents the lute from. adhering. The lute, when applied, is to be covered with slips of linen spread with the lime lute ; which slips are to be fastened...