1818-5 On the Blow-pipe. 45 



transparent beads of the compound with microcosmic salt and 

 with borax be fused together, the triple compound becomes 

 opaque and white. Flies off by reduction? 



Oxide of Uranium. The yellow oxide by ignition becomes 

 green or greenish-brown. With microcosmic salt in the interior 

 flame it forms a clear yellow glass, the colour of which becomes 

 more intense when cold. If long exposed to the exterior flame, 

 and frequently cooled, it gives a pale, yellowish, red-brown 

 glass, which becomes greenish as it cools. With borax in the 

 interior flame a clear, colourless, or faintly-green glass, is 

 formed, containing black particles, which appear to be the 

 metal in its lowest state of oxidation. In the exterior flame this 

 black matter is dissolved if the quantity be not too great, and 

 the glass becomes bright yellowish-green, and after further 

 oxidation yellowish-brown. If brought again into the interior 

 flame, the colour gradually changes to green, and the black 

 matter is again precipitated, but no further reduction takes 

 place. 



Oxide of Manganese gives with microcosmic salt in the exterior 

 flame a fine amethyst colour, which disappears in the interior 

 •flame. With borax it gives a yellowish hyacinth -red glass. 



When the manganese from its combination with iron, or any 

 other cause, does not produce a sufficiently intense colour in the 

 glass, a little nitre may be added to it while in a state of fusion, 

 and the glass then becomes dark-violet while hot, and reddish- 

 violet when cool : is not reduced. 



Oxide of Tellurium, when gently heated, becomes first 

 yellow, then light-red, and afterwards- black. It melts and is 

 absorbed by the charcoal, and is reduced with a slight detona- 

 tion, a greenish flame, and a smell of horse-radish. Microcosmic 

 salt dissolves it without being coloured. 



Oxide of Antimony is partly reduced in the exterior flame, and 

 spreads a white smoke on the charcoal. In the interior flame it 

 is readily reduced by itself, and with soda. With microcosmic 

 salt and with borax it forms a hyacinth-coloured glass. Metallic 

 antimony, when ignited on charcoal, and remaining untouched, 

 becomes covered with radiating acicular crystals of white oxide. 

 Sulphuret of antimony melts on charcoal, and is absorbed. 



Oxide of Bismuth melts readily in a spoon to a brown glass, 

 which becomes brighter as it cools. With microcosmic salt it 

 forms a grey-yellow glass, which loses its transparency, and 

 becomes pale, when cool. Add a further proportion of oxide, 

 and it becomes opaque. With borax it forms a grey glass, 

 which decrepitates in the interior flame, and the metal is reduced 

 and volatilized. It is most readily reduced by itself on charcoal. 



Oxide of Zinc becomes yellow when heated, but whitens as it 

 cools. A small proportion forms with microcosmic suit and with 

 borax a clear glass, which becomes opaque on increasing the 

 quantity of oxide. A drop of nitrate of cobalt being added to 



