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WRIGHT: ELECTRICAL GONIOMETER FURNACE 



PHYSICS. — An electrical goniometer furnace for the measurement 

 of crystal angles and of refractive indices at high temperatures. 

 Fred. Eugene Wright. Geophysical Laboratory. 



The measurement of the change in the optical properties and 

 in the interfacial angles of crystals with change in temperature 

 has long interested mineralogists, and many attempts have been 



Fig. 1. Photograph of Goldschmidt's two circled goniometer with thermo- 

 electric furnace attachment mounted in position ready for measurements. Ai, A2, 

 upper and lower water jackets; Pi, P2, rubber tubing for circulation of water thru 

 Ai, A2; Fi, F2, platinum wires, 0.4 mm. in diameter, of heating spirals in furnace; B, 

 crystal holder extending into center of furnace; T^, T2, thermoelement wires. 



made, since the pioneer work of Schrauf and Mallard, to devise 

 satisfactory methods for the purpose. The introduction oi elec- 

 trical methods and appliances has greatly simplified the problem 

 and recently F. Rinne^ has successfully adapted aa electric re- 



1 Neues Jahrb. Min. Geol. u. Pal, 1910, II, 13! 



