A Treatise on Heat Volume 1; The Thermometer Dilatation Change of State and Laws of Vapours (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1849 Excerpt: ...at temperatures near that of boiling water; tin, bismuth, and lead, are liquefied below a red heat; silver may be melted in a common fire urged by a bellows, gold and copper in a wind furnace, and iron has been melted in a small quantity in a draught furnace. The most intense heat, however, capable of being produced in the best furnaces, fails to affect platina. This metal, however, yields to the heat of the oxy-hydrogen blow-pipe, and to that generated between the poles of a powerful galvanic battery. By means of the former apparatus Dr. Clarke reduced 100 grains of platina to a state of fusion, and kept it liquid for some minutes. Iridium is also melted in small globules by the same powerful sources of heat, as also lime, magnesia, and silica. There are some substances, again, whose fusion cannot be effected unless they are operated on under great pressure. This is owing to their extreme volatility in the liquid form, which causes them to pass directly, as it were, from the solid to the gaseous state, under the ordinary atmospheric pressure. Thus Sir James Hall succeeded in melting chalk (carbonate of lime) confined in the end of a gun barrel, under the pressure of the atmosphere of carbonic acid gas, disengaged by the action of heat, and converted it by this means into crystalline marble. Carbon, it has been observed, whether under the form of diamond or of charcoal, has never been fused. When exposed to high temperatures in contact with oxygen, this substance undergoes combustion. Messrs. Hare and Silliman, indeed, announced that they had melted charcoal in small globules between the poles of a peculiar form of galvanic battery with large surfaces, called a deflagrator; but there is no doubt that those globules consisted, not of molten charcoal, but of ...