264 Scientific Intelligence. 
out its entire cen the light emitted normally was in the same 
state of polarization. Keeping the positions of the Nicol and the 
selenite constant, the same colors were observed throughout the 
then placed myself near the end of the / Speer as it issued from 
and more obliquely at the beam, observ “he colors fading unti 
they disappeared. Augmenting the obliquity the colon wi eet: 
ce more, but one were now complementar to . sr 
in the faikicsesy Even the uncondensed electric let falling on 
the floating matter showed, though faintly, the effects of polariza- 
tion.* 
n the air was so sifted as to entirely remove the visible float- 
ing sito, it no longer exerted any sensible action upon the light, 
but beh wed like a vacuum. 
was diffused the smoke of ation He also operated on tobacco 
smoke. His first brief communication stated the fact of polariza- 
tion by a smoke, but in his second communication he annoul 
covery of a neutral point in the beam, at the opposite 
oo whish the light was polarized in planes at right angles to 
But unlike e my observations on the laboratory air, and unlike the 
action of the sky, the direction of maximum’ polarization in 
e question was left in this condition, an i 
am not aware that M. Govi or any other investigator has purs 
it further. din the 
had noticed, as before stated, that as the clouds formed in 
experimental tube became panei the polarization of re light 4 8 
charged at right angles to the beam became weaker, 
of maximum polarization becoming oblique to the are Expert 
ments on the fumes of chlorid of ammoniam gave me also reasoP 
3 pattie try Alpine air 
t Cor mptes Rendus; tome li; pp. 360 and 669. 
ese, 
