. Penfield and Pearce — Polyhasite and Tennantite, etc. 15 



18. Conclusion. — The results of this lone and tedious inves- 

 tigation may be stated in a few words. The mean values of 

 the absolute heat conductivity, k, of thymol, obtained from 

 the measurements as a whole are in g/cs. 



Solid thymol, 12° 10 8 X& = 359 

 Liquid thymol, 13°, 10 6 X&'= 313 



The mean values of thermometric heat conductivity x, are in c 2 /s> 



Solid thymol, 12°, 10 B X x = 1077 

 Liquid thymol, 13°, 10 6 X x = 691 



Hence the increment of heat conductivity, encountered on 

 passing from liquid to solid, at say 13°, referred to solid con- 

 ductivity, 



(k—k')/k = -13, (x-k')Ih = -36 ; 



and the corresponding increment referred to liquid conduc- 

 tivity is 



(k — k')/k' = -15, (k — h')/x' = -56 



Now since in all questions relative to thermal flux, it is the 

 thermometric conductivity which enters fundamentally into 

 the considerations, the importance of the effect produced when 

 any part of the substance changes state is obvious. 



Art. II. — On Polyhasite and Tennantite from the Mollie 

 Gibson Mine in Aspen, Colorado y by S. L. Penfield and 

 Stanley H. Pearce. 



During the past year the Mollie Gibson Mine has been 

 one of the most productive in Colorado. Our attention was 

 first called to the sj)ecimens from there by Dr. Richard Pearce 

 of Denver, who sent a few to New Haven for identification. 

 Later Mr. C. E. Palmer, general Manager of the Mollie Gibson 

 Consolidated Mining and Milling Company, generally supplied 

 us with specimens and information concerning their occurrence. 

 We take pleasure in expressing to both of these gentlemen our 

 thanks for their courtesy. From Mr. Palmer's annual report 

 to the stockholders for the year 1891, of his company we quote 

 some figures, which are of interest as showing the wonderful 

 richness of the mine. Most of the production dates from the 

 month of March, when the rich ore was first encountered, and 



