THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOUHNAL OF SCIENCE. 



[FIFTH SERIES.] 



JULY 1892. 



I. The Fusion Constants of Igneous Rock. — Part I. The 

 Measurement of High Temperature. By Carl Barus*. 



[Plate I.] 



Introductory. 



1. "DLAN of the Work. — The present paper opens a series 

 of three researches made at the request of Mr. 

 Clarence King, for the purpose of elucidating certain funda- 

 mental questions in dynamic geology. The first paper is 

 introductory, as stated above ; the second f will investigate 

 the amount and the character of the thermal contraction of 

 a molten magma passing from liquid to solid ; while the last 

 paper J, in addition to furnishing data for the thermal capacity 

 and the latent heat of fusion under the given conditions, has 

 for its chief purpose the determination of the relation of 

 melting-point to pressure. I will anticipate here sufficiently 

 to state that not only is the rock-contraction specified 

 thoroughly normal in type, but solidification occurs sharply 

 at a definite temperature. Again, compatibly with the distinct 

 value for the latent heat of fusion, the datum found for the 

 pressure-coefficient of the melting-point of the silicate is of an 

 order identical with the corresponding constant found for 

 organic bodies, fusing normally. 



* Communicated by the Author. 



t See note in American Journal, December 1891. 



\ See note in American Journal, January 1892. 



PhiL Mag. S. 5. Vol. 34. No. 206. July 1892. B 



