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Scientific Intelligence. 



timeters below the bottom of the cavity. The space between the cruci- 

 ble and the walls of the cylinder must be 5 or 6 centimeters. In using 

 a lime crucible, charcoal is first to be introduced, little by little, till the 

 crucible is covered, the heat is then very gradually increased till the 

 crucible becomes red, when the coals are removed to make sure that the 

 crucible is not cracked, after which the heat may be urged to the utmost. 

 The second kind of crucible is of carbon. The author uses gas-retort 

 carbon and fashions it on a lathe. To free the material from impurities 

 it may then be strongly heated in a current of chlorine, by which pro- 

 cess it loses weight. These crucibles are placed within crucibles of lime, 

 the intervening space being filled with calcined alumina. The third 

 species of crucible is made of alumina, obtained by calcining ammonia- 

 alum. Thus prepared it is plastic, but shrinks much on drying. To 

 prevent this, the author mixes the mass with a calcined mixture of alu- 

 mina and marble. A mixture of plastic alumina, calcined alumina and 

 aluminate of lime, in equal parts, gives a very hard and infusible mass, 

 which softens a little at the melting point of platinum. Once baked, 

 these crucibles resist all tests ; even sodium has no action on them. The 

 lime crucibles may be used whenever the alkali is not injurious ; the 

 carbon crucibles have a more limited use in consequence of their reduc- 

 ing agency. The alumina crucibles may be used almost always when 

 lime will not answer. With respect to the heat produced by this fur- 

 nace the author gives the following details. Platinum fuses in a crucible 

 of lime into a single well-united button. This platinum possesses prop- 

 erties very different from those of ordinary platinum condensed from the 

 sponge. When copper is plated with the fused platinum rolled out into 

 a very thin sheet, nitric acid has no action whatever, as it does not pene- 

 trate the leaf of metal. A plate made from fused platinum does not 

 cause the union of oxygen and hydrogen even after several hours. Fused 

 platinum possesses a perfect softness and malleability. In a crucible of 

 carbon, platinum melts easily but yields a brittle alloy of platinum, carbon 

 and silicon. By raising the heat above the temperature required for 

 fusion, Deville succeeded in volatilizing the metal with remarkable ease, 

 so that it condensed in small globules. Pure peroxyd of manganese 

 heated with carbon from sugar in quantity less than sufficient to reduce 

 the oxyd, gave fused metallic manganese as a brittle mass, having a rose 

 reflection like bismuth and as easily reduced to powder. Its powder 

 decomposed water at a little above the ordinary temperature. Chromium 

 as prepared in a similar manner was well fused, but not into a button, at 

 the temperature at which platinum volatilizes. The metal is brittle and 

 cuts glass like a diamond. It is easily attacked by chlorhydric acid, but 

 little by sulphuric acid, and not at all by nitric acid either strong or 

 weak. Metallic nickel fuses to a homogeneous button which may be 

 forged with great facility. It has a ductility almost without limit and is 

 more tenacious than iron in the ratio of 90 to 60, according to Werth- 

 eim's experiments. This nickel contained traces of silicon and copper. 

 Fused cobalt is as ductile as nickel and still more tenacious. According 

 to Wertheim its tenacity is to that of iron as 115 to 60, or nearly double. 

 The most refractory body which the author fused was silica, which, 

 however, in quantities of 30 grammes was not perfectly liquified. The 



