450 Scientific Proceedings^ Royal Dublin Society. 



from the platinum. Enamels may be readily obtained in oxidizing and 

 reducing atmosplieres, and the colours produced examined at any 

 temperature under progressive conditions of saturation from the centre to the 

 point at which the colour fades away. Uraniuite, for example, dissolves in a 

 drop of mioroeosmic salt in air, yielding a greenish yellow-glass with tints 

 varying from liglit yellow to deep orange when hot, from colourless to 

 yellow when cold. In sodium carbonate uraiiinite powder disintegrates in a 

 distinctive manner, producing finally a slag of mottled yellows and browns 

 which remain unchanged on heating. 



Table. 



{Temperatures in. Drgrces Centigrade.) 

 Fluorides. 



Yttrocerite (Finbo, Sweden) : — infusible below 1570. 

 Yttrocerite (Finbo, Sweden, 1691)' : — infusible below 1510. 



Orthosilicates. 



Zircon \_Cyrtolite'\, (North Carolina): — Eeddens blue litmus paper. 

 Decomposes, yielding a sublimate at 1160, but does not flow freely below 

 1560. 



Thorite (loc. unknown) : — shows signs of melting at 1270 and flowing at 1420. 



Thorite [Orangife2 (Arendal, Norway) : — is difficult to distinguish, probably 

 fuses at 1255 and loses body, but does not flow freely below 1590. 



Tliorite [Uranothorite^ (E-isor, Norway) : — is difficult to distinguish. Melts 

 at 1270, but does not flow freely below 1450. 



GadoUnite (Arendal, Norway) : — reddens litmus paper, lightens in colour, 

 and sometimes yields a white sublimate. Possibly melts at 1395, and 

 certainly at 1450, showing iridescence and sublimation. The fusion, 

 which first spreads over the platinum support in a meshwork, finally 

 collects into globules. 



liisbriie (Risor, Norway) : — softens and finally flows slowly at about 1720. 



Allanite (Saetersdalen, Norway) : — reddens blue litmus. Softens and 

 becomes bright below 1220, fuses at 1255 to a brown glass and flows 

 readily with iridescence. The fusion shows on heating the colour- 

 changes previously described. 



1 Some of the specimens examined are from among those which have been described and identified 

 by Prof. Apjohn in the " Catalogue of the simple minerals in the systematic collection of Trinity 

 College, Dublin," to which the numbers refer. 



