Chemistry and Physics. 457 
antilogous pole is different from the conductivity in the opposite 
direction. Franz panes has examined the subject, using an 
adaptation of Weber’s thermo-electrical method, and conclu 
that the unilateral condustivity for heat in tourmaline is at oe 
extremely small and probably does not exist.— Phil. Mag., Nov., 
1884, pp. 427-433 
9. Helmholtz’ dispersion theory. — A. WULLNER shows “from 
the pats vations pate angley that the equation between indices of 
an Chemie, No. 10, 1884, pp. 306 6-312. +E. 
The Infra-r red Emission-spectra ne rage wae » Vapors 3 by 
i. pee EREL.—Last year I submit the A mie des 
Season a short account of my first Pest on ie infiered 
Spectra emitted by metallic set till then unknow Sine 
that time I have investigated the subject still further by aking 
use of a special a shoe which shall be page in a future 
: a 
throwing the s a eg about to be examin oom upon a suitable 
Bicephoasnes. substance, which nes been previously rendered 
luminous, and in observing the temporary excitation, which 
recedes " extinction, under the tins of the infra-red rays. 
he lines and bands of the emission-spectra then appear brilliant, 
and can be examined with the microscope. 
In experimenting on different phosphorescent substances, nota- 
bly certain al. eseaapcme of sulphide of calcium, I found some 
uch more sensitive than others for infra-red rays. These sub- 
staunes have permitted fi to determine directly the wave-lengths 
or the more brilliant lines of several ee metallic 
vapors (potassium, qoltae m, cadmium), by using the diffraction- 
spectra produced by a very beautiful metal gratis of Mr. Ruth- 
erfurd’s, which was kindly lent be by M. Mascart. 
ther m tals, the spectra were obtained ie means of a bi- 
red of the solar spectrum have been again + dole a byt mea 
of the grating, which had been stud ervice; an the 
more sensitive substances in my possession have permitted me to 
extend these measurements much f I was enabled to 
do in my previous ersmeiraseee! propose to return shortly to 
* Comptes Rendus, t. xcvii, p. 7 
¢ Annales de Chimie et de of Sa 5* série, t, xxx, p. 5. 
