Intelligence and Miscellaneous Articles. 2>21 



tions of the form 



log a* = a — bt -f- ct 2 . 



(1) For common glass, of density 2-539, expressing the resist- 

 ances per cubic centim. in millions of megohms, we get the following 

 results : — 



Temperatures. Eesistauees. 



+ 61°-2 0705 



+20° 91-0 



-17° 7970-0 



In order to form an idea of the magnitude of this last resistance, 

 it may be remarked that it represents nearly twice the resistance of 

 a copper wire, of 1 square milium section, reaching from the earth 

 to Sirius. 



The whole of the results obtained upon common glass are ex- 

 pressed by the formida 



log x = 3-00507 - 0-052664 x t + 0-00000373 x t\ . 



The term of the second order being very small, the values of 

 logo-' are represented by a line which differs but little from a 

 straight line. The resistance varies nearly ^ of its value for each 

 degree of temperature. 



(2) Bohemian glass of density 2-431, upon which I worked, has 

 from 10 to 15 times the conductivity of common glass at the same 

 temperatures. Its resistance is given by the formula 



log ^=1-78300 -0-049530 x t+ 0-0000711 x t\ 



(3) The crystal tried has for its density 2-933 ; and it, contrary 

 to Bohemian glass, has from 1000 to 1500 times the insulating- 

 power of ordinary glass at the same temperatures. Its conductivity 

 only begins to be manifest at above 40°. 



At 40°-2 its resistance is equal to 6182 



At 105° „ „ 11-6 



The results are represented by the formula 



log x = 7-22370 -0-088014 x t + 0-00028072 x f. 

 — Comptes Bendus de VAcademie des Sciences, July 31, 1882, t. xcv. 

 pp. 216-818. 



ON THE SUKF ACE-TENSION OP SOME LIQUIDS IN CONTACT WITH 

 CAEBONIC ACIDf. NOTE BT S. WROBLEWSKlJ. 



If instead of water we take a liquid which mixes in all propor- 

 tions with liquid carbonic acid — for instance, alcohol, essential oil 



* The experiments were made in M. Jamin's laboratory at the Sor- 

 honne. 

 f Abstract by the Author. 

 % See the preceding Note, Phil. Mag. Sept. 1882, p. 236. 



