Chemical Manipulation: Being Instructions to Students in Chemistry, on the Methods of Performing Experiments of Demonstration Or of Research, with Accuracy and Success

W. Phillips, 1827 - 646 páginas

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Página 51 - A solid immersed in a liquid is buoyed up by a force equal to the weight of the liquid displaced.
Página 51 - ... also a number of small rings of fine brass wire made in the manner first mentioned by Mr. Lewis, by appending a weight to the wire, and coiling it with the tension of that weight round a thicker brass wire in a close spiral, after which the extremity of the spiral being tied hard with waxed thread, I put the covered wire in a vice, and applying a sharp knife which is struck...
Página 100 - ... with soda is put into an acid. It has evidently not been intended to enumerate all the means by which the presence of each acid in the soda bead could be perceived or established. Little has been said beyond what appeared required and sufficient. Mention has been made above of small plates of clay. They are formed by extending a white refractory clay by blows with the hammer, between the fold of a piece of paper, like gold between skins. The clay and paper, are then cut together with scissars...
Página 53 - ... most times very inconvenient fractions of the grain. I have found that a preferable method is to ascertain the weight of a certain length of wire, and then take the length of it which corresponds to the weight wanted. If fine wire is employed, a set of small weights may be thus made with great accuracy and ease. Inconvenience from the length of the wire in the higher weights is obviated by rolling it round a cylindrical body to a ring, and twisting this to a cord. This little balance is a very...
Página 51 - ... the same time on a flat hone, that the extreme surfaces of them may be in the same plane ; and their distance is such that the needle when laid across them rests on them at a small distance from the sides of the beam. They rise above the surface of the table only one and a half or two-tenths of an inch, so that the beam is very limited in its play.
Página 144 - There are two great and general objects to be gained by solution, which render it a process of constant occurrence in the laboratory. The first is that of preparing substances for the exertion of chemical action ; and from the perfect manner in which it separates the particles one from another, every obstacle dependant upon the attraction of aggregation is removed, at the same time that other advantages are obtained. The second object is that of separating one substance from another ; this being...
Página 289 - If the surface of water be 19 inches by 28, and a well be formed at one end of 14 inches by 10, and 12 inches in depth, so as to leave a continuation of the shelf surface on three sides of the well, of two inches and a half in width, it will be found sufficiently large for almost every purpose. Such a trough is best made of japanned copper, and supported in a wooden frame, so as to stand about 39 inches from the ground. Two depressions like small wells, should be made in the shelf, each about seven...
Página 51 - I can learn the weight of any little mass from one grain, or a little more, to the y^^ of a grain. For if the thing to be weighed weighs one grain, it will, when placed on one extremity of the beam, counterpoise the large gold weight at the other extremity.
Página 516 - ... first experiments, and therefore he does not take time to put them in order ; he prosecutes with eagerness the experiments which he has last thought of, and in the mean time the vessels employed, the glasses and bottles filled, so accumulate, that he cannot any longer distinguish them, or at least he is uncertain concerning many of his former products. This evil is increased if a new series of operations succeed, and occupy all the laboratory ; or if he be obliged to quit the place for some time,...
Página 80 - It is sufficiently powerful to melt pure iron in a crucible, in twelve or fifteen .minutes, the fire having been previously lighted. It will effect the fusion of rhodium, and even pieces of pure platinum have sunk together into one button in a crucible subjected to its heat. All kinds of crucibles, including the Cornish and the Hessian, soften, fuse, and become frothy in it ; and it is the want of vessels which has hitherto put a limit to its applications.

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