102 



common limestones vitrify with facility, granular white marble 

 crumbled as it lost its acid, and its particles vere dispersed, 

 but in some instances I have seen its angles rounded and glaz- 

 ed. The difficulty of flising it proceeds, chiefly from its white- 

 ness, by which much heat is lost. 



The metals are fused, and their oxides reduced in every in- 

 stance which I tried, but unless we operate on large masses the 

 reguli are burnt at the moment of their formation ; these de- 

 compositions are produced by the excess of hydrogen, and some 

 of the metals which form carbiu'ets can be obtained in purity 

 only by this method ; for example, manganese and nickel ; a 

 fragment of rutilite fused, and the reduced titanium burnt with 

 violence. Oxide of tungsten gave a button, but too small to 

 take its S. G. A piece of manganese Avas fused, and kept for 

 some time, when an excess of oxygen was admitted it defla- 

 grated violently. A globule of copper was vaporised with a flame 

 of great splendoiu" ; gold, silver, and platina are dissipated, not 

 in flame, but by a vehement ebullition which throws their par- 

 ticles to a distance. 1 lay before the Academy a button of this 

 last metal, weighing 72 grs. which was obtained by fusing on 

 charcoal, 3 globules of it weighing 84 grs. so that no less than 

 12 grs. were dissipated. This enormous loss arose from the 

 direction of the blowpipe, for altering which I had made no 

 provision, and as platina is a very bad conductor of caloric, 

 that portion of it which was next the flame was boiling before 

 the more remote part was fused. However it was fused in less 

 than three minutes, and remained liquid some time after it was 

 removed from the flame, so that I am confident it might be 

 cast in moulds, and by making four or five of these flames coii- 



I 



