Wells's Principles and Applications of Chemistry: For the Use of Academies, High-schools and Colleges

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Ivision, Phinney & Company, 1862
 

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Página 396 - Platinum exists in two states of minute subdivision, viz., as spongy platinum, and platinum black. The properties and preparation of spongy platinum have been already described (§§ 48, 296). Platinum black is the metal in a state of such fine subdivision, that it has the appearance of soot. It is easily prepared by slowly heating, to 212° F., with frequent agitation, a solution of chloride of platinum, to which an excess of carbonate of soda and a quantity of sugar have been added. The precipitated...
Página 169 - ... even so very hard as never to wear or break in pieces, no ordinary power being able to divide what God himself made one in the first creation.
Página 492 - The blood is not an organ which is formed, but an organ in the act of formation ; indeed, it is the sum of all the organs which are being formed. The chemical force and the vital principle hold each other in such perfect equilibrium, that every disturbance, however trifling, or from whatever cause it may proceed, effects a change in the blood.
Página 196 - Let us for an instant contemplate the enormous amount of oxygen employed in the function alone of respiration, which may be considered in the light of a slow combustion. For the respiration of human beings, it has been calculated that no less than one thousand millions of pounds of oxygen are daily required, and double that quantity for the respiration of animals, whilst the processes of combustion and fermentation have been calculated to require one thousand millions of pounds more. But, at least,...
Página 386 - At a dull red heat this oxide is again decomposed into its constituents. Hydrochloric acid has little or no action on mercury, and the same may be said of sulphuric acid in a diluted state ; when the latter is concentrated and...
Página 152 - One end of the solenoid coil is connected with the positive, and the other with the negative pole of the...
Página 492 - ... come in contact with any organ in the body, without yielding to its attraction. The slightest action of a chemical agent upon the blood exercises an injurious influence ; even the momentary contact with the air in the lungs, although effected through the medium of cells and membranes, alters the color and other qualities of the blood.
Página 225 - Under what circumstances does it vary? greater in summer than in winter, and during night than during day. It is also rather more abundant in elevated situations, as on the summits of high mountains, than in plains ; this is probably owing to an absorption of the gas near the surface of the earth by plants and moist surfaces.
Página 399 - The plan of obtaining permanent phetographic images upon paper was originally devised by Mr. Talbot of England in 1839. The process first followed consisted in soaking ordinary writing-paper in a weak solution of common salt, and when dry washing it over on one side with a solution of nitrate of silver. This operation was performed by candle-light, and the paper dried by a fire. The sheet thus prepared, when laid under an engraving or leaf, and exposed to diffused daylight for a period of about half...
Página 209 - Water .—Water, as has been already stated, i:.s formed by the union of two volumes of hydrogen and one of oxygen, or by weight, of 8 parts of oxygen to 1 of hydrogen. The composition of water by measure and by weight, upon which, as a basis, the whole theory of atomic constitution and the doctrine of equivalent proportions rests, may be proved •by a great variety of experiments, both by analysis and by synthesis. By analysis, by decomposing water by the galvanic current (§ 242, p. 148), and...

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