The Technical repository, by T. Gill

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Thomas Gill (patent-agent)
1822
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Seite 76 - A hole is then made in a piece of charcoal, and filled with the paste, and its surface smoothed by pressure with the agate pestle. It is then to be gently heated by the blowpipe, till it is perfectly dry. (The soda only assists the cohesion, and may be omitted.) The assay, previously fused with lead, is placed in the middle of the little cupel, and the whole heated by the exterior flame. When the operation is finished, the precious metals are left on the surface of the cupel. This experiment is so...
Seite 222 - Staves and heading also, must be rived the same way of the grain, in order to pass inspection. The Mill -sawed lumber, which, I believe, is now universally used in the Middle and Southern States, and in the West Indies, for covering the walls of wooden buildings, is partly cut in a wrong direction of the grain, which is the...
Seite 223 - ... particularly as to heading, of which at least double the quantity may be obtained by this mode of sawing, to what can be procured in the common method of riving it ; nor is the straight-grained or good rift indispensable for the saw, as it is for the purpose of being rived. The heading, when sawed, is in the form it should be, before it is rounded and dowelled together, all the dressing required being merely to smooth off the outsides with a plane. Timber for staves ought to be straight in order...
Seite 248 - ... give evident tokens of their being able to produce shoots of sufficient strength. When they are thus shortened that they may appear regular, let a small hoop be placed within the branches, to which the shoots are to be fastened at equal distances ; by this practice two considerable advantages will be gained, the trees will grow more regular, and the middle will be kept hollow so as to admit the influence of the sun and air ; but this in a large plantation would be almost impossible, nor indeed...
Seite 15 - But, from the properties of the lever, forces which are to each other inversely as their distances from the fulcrum, or...
Seite 81 - Very different statements have been given of the composition and origin of Tutenag, used by the Chinese in the formation of many of their metallic utensils. According to Keir, it is a white alloy of copper, zinc, and iron which is very hard and tough, but at the same time malleable and taking on a fine polish. An inferior sort of it, according to the same author, is more of the colour of brass.
Seite 233 - The small jets adapted to the extremity of the beak are a great improvement, for the extremity is liable soon to become covered with soot, and the hole to be either blocked up, or lose its circular form, and it is necessary to clean it, and clear the opening with a small needle kept at hand for the purpose. This is an indispensible but troublesome operation.
Seite 82 - ... a fine polish. An inferior sort of it, according to the same author, is more of the colour of brass. De Guigne, on the contrary, states that its properties, especially that of imparting to copper a white colour, and rendering it less liable to acquire verdigris on its surface, prove that it does not contain zinc. According to him, it is an alloy of iron, lead, and bismuth. Engestroem, in the Stockholm Memoirs, states that the Pak-Fong, or white copper of China, is composed of copper, nickel,...
Seite 232 - ... of ivory. The hands, too, if not quite dry, contract the same odour during the operation, especially if the blowpipe has not been used for some time, and was not well cleaned before it was laid by. Tin plate is not liable to this nuisance, and has, besides, the advantage of cheapness. When that material is employed, the joinings should be made air tight by inserting pieces of paper between them. Notwithstanding that silver is the best conductor of heat of all the metals, no inconvenience need...
Seite 352 - Snow-hill, in the City of London, Esq. in consequence of a communication made to him by a certain foreigner, for an improved method of generating steam.—15th June—6 months.

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