A Manual of Useful Knowledge: Being a Collection of Valuable Miscellaneous Receipts and Philosophical Experiments, Selected from Various Authors

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Page 40 - ... about three inches, when well immersed and stirred about therein. The feathers when thoroughly moistened will sink down, and should remain in the limewater three or four days ; after which the foul liquor should be separated from them by laying them in a sieve.
Page 32 - If necessary, the person at the top, who has hold of the other end of the rope, draws the bush up again ; but, in this case, the person below must turn the bush, to send the wood end foremost, before he calls to the person at top to pull it up. Many people, who are silent to the calls of humanity, are yet attentive to the voice of...
Page 30 - The greater the difference is between the height of the two wells, the faster the water will filter ; but the less it is, the better, provided a sufficient quantity of water be supplied by it. This may be practised in a cask, tub, jar, or other vessel. The...
Page 168 - ... the yellow rind is completely absorbed. Those parts of the sugar which are impregnated with the essence are, from time to time, to be cut away with a knife, and put into an earthen dish. The whole being thus taken off, the sugared essence is to be closely pressed, and put by in pots, where it is to be squeezed down hard ; have a bladder over the paper by which it is covered, and tied tightly up. It is at any time fit for use, and will keep for many years. Exactly...
Page 112 - You must likewise be sure to make the glass as clean as possible on the side intended to be silvered, and have the paper also quite clean ; otherwise, when you have drawn the paper from under it, dull white streaks will appear, which are very disagreeable. After the paper is drawn out, place as many weights upon the glass as you conveniently can, in order to press out the superfluous mercury, and make the foil adhere to the glass. When it has lain six or seven hours in this situation, raise the stone...
Page 111 - ... extremely true, with a frame round it, or a groove cut in its edges, to keep the superfluous mercury from running off; secondly, lead weights covered with cloth, to keep them from scratching the glass, from one pound weight to twelve pounds each, according to the size of the glass laid down ; thirdly, rolls of tin-foil ; fourthly, mercury. The artist...
Page 191 - ... two ounces of borax in a pint of boiling water, and adding to the solution as much slaked lime as will make it into a thin...
Page 211 - If a fire be made in a large room, and a smooth, wellpolished mahogany table be placed at a good distance near the wall, before a large concave mirror, so that the light of the fire may be reflected from the mirror to its focus on the table ; if you stand by the table, you will...
Page 39 - ... and preserve the liquor for use. The article to be cleaned should then be laid upon a linen cloth on a table, and having provided a clean sponge, dip...
Page 189 - Take an ounce of white wax, and the same weight of gum mastich powdered. Put the wax in a glazed earthen vessel over a very slow fire ; and when it is quite dissolved, strew in the mastich, a little at a time, stirring the wax continually until the whole quantity of gum is perfectly melted and incorporated : then throw the paste into cold water, and when it is hard, take it out of the water, wipe it dry, and beat it in one of Mr.

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