110 Scientific Intelligence. 
SCIENTIFIC INTELLIGENCE. 
I. CHEMIsTRY AND Puysics. 
he influence of the direction a transmission upon the passage 
of ruin heat through crystals—Knostaucu has published the sec- 
ond portion of his very elaborate and skillful Neapa rare of this inter- 
sei subject. We shall give his results in his own wo 
adiant heat penetrates certain crystals of the oan biaxial 
systems, like Dichroite, Topaz, Diopside, &c., in different quantities in 
different directions. It ses, for instance, most freely through di- 
chroite in the direction of the middle line, less freely in a direction per- 
pendicular to the plane of the optic axes, and least freely of a 
direction parallel to the supplementary lin lue topaz, on t 
contrary, it pa in the smallest proportion in the direction of the 
middle line, more abundantly perpendicular to the plane of the optic 
the crystal, exhibit different properties in their behavior for example 
toward diatherma anous hon In this particular different crystals ex- 
tion. Thus’ rays of heat whoee wheres ‘of polarization coincides with 
&e. 
ae of heat polarized in different planes often differ from each 
other in their capacity to penetrate diathermanous bodies after their 
passage through the crystal. € comparison of the rays polarized in 
the same sense and transmitted in the same direction exhibits the great- 
est variety, not only in different crystals but even in those belonging to 
the same nip 2 sete as yellow and blue topaz, 
In on the same substance, as for attiagis mica, the quantitative 
as els as ot oninaiive differences of the rays polarized in in different 
planes increase with the thickness of the layers penetrate 
When the heat passes successively through two plates of the same 
crystal, e. g. Pistacite, phenomena are observed analogous to those 
already mentioned according as the planes of the optic axes coincide 
or are crossed. 
II. When the rays of pe pass through certain crystals of the opti- 
cally uniaxial systems, as amethyst, idocrase, &c., quantitative as l 
as qualitative differences are gphbind according as the rays penetrate 
the crystal in one or another direction. 
However great these differences are in the cases of transmission pat- 
allel and and perpendicular to the axis, no difference of any kind is per- 
oa in the behavior of rays of heat which, whatever may be their 
are all — at re eee to the axis. 
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