The Year-book of Facts in Science and Art

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Simpkin, Marshall, and Company, 1840
 

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Page 59 - The following method will be found to answer that purpose, and its simplicity is such as to require no particular care or management on the part of the workmen : Take of impure copper ... . 100 parts ; Copper scales 10 parts ; Ground bottle glass, or any other flux 10 parts ; heat the whole together in a covered crucible, and keep the copper in a state of fusion for twenty minutes or half an hour, at the end of which time it will be found at the bottom of the crucible perfectly pure....
Page 193 - I could learn from the natives, they do not reach their full growth till 29 between nine and ten years of age, which, if true, brings them extremely near the human species, as the boy or girl of West Africa, at thirteen or fourteen years old, is quite as much a man or woman as those of nineteen or twenty in our more northern clime.
Page 80 - ... parts which are exposed to the south and south.west winds, found in some instances to be fast mouldering away. Colour is of more importance in the selection of a stone for a building to be situated in a populous and smoky town than for one to be placed in an open country, where all edifices usually become covered, as...
Page 74 - ... if the emulsive mixture be stirred ; but the addition of water is necessary to prevent the coagulated caoutchouc from sticking to the sides or bottom of the vessel and becoming burnt. In order to convert the spongy mass thus formed into good caoutchouc, nothing more is requisite than to expose it to moderate pressure between the folds of a towel. By this process the whole of the aloetic extract, and other vegetable matters, which concrete into the substance of the balls and junks of caoutchouc...
Page 165 - ... of the precipitate. The quantity of Prussian blue produced from a given weight of pearlash or potash is generally about one-fourth of the weight of the pure potash contained in the salt ; but the larger the quantity operated upon at one time, the larger is the relative produce. Thus six ounces of pearlash, containing 45 per cent, of alkali, yielded only 295 grains of Prussian blue, whilst one pound of the same pearlash yielded 1355 grains. The Prussian blue here spoken of is the pure perferrocyanate...
Page 237 - ... of small springs coming to the surface may be obviated. The theory of the earth's internal drainage is so simple, that every man of common sense would be able to drain his lands upon sure principles, or else to know precisely why it cannot be drained, if he were to become so much of a geologist, as to learn what rocks existed under his land, at what depth, and in what positions.
Page 270 - At half past two o'clock, the spectacle changed to darkness, which, on dispersing, displayed a luminous rainbow in the zenith of the heavens, and round the ridge of darkness that overhung the southern portion of the country. Soon...

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