New-York daily tribune. [volume] (New-York [N.Y.]) 1842-1866, 1851-01-30
SCIENCE.
Lnte Scientific Intelligence...,No XVI.
Carefully Prepared for The Tribune.l
RESEARCHES ON LIGHT.


nv of Sciences paper relative to his further re-
searches on Light We append an abstract OF the
results attained. Up to the present time no
means have been furnished OF measuring the
quantities of polarzed light contained In ray re-
hected by a surface which does not complete
" polarize the light. NJ. Arago, by employing
pile ofgess plates placed so as to incline suitably
on the track of a reflected ray, so as to obtain
neutral light has found that at an equal number
Of degrees above and below the angle OF mss, mss
,nro ation the proportion OF polarZed llBut
Contained In raw was the same, a TACT which mas
enabled him to determine the angle OF the maxi
mum polarization of certain metals,-such, Tor
instance as steel and mercury,-and thence TO de-
dnce by the well known law OF Brewster, the IN
dex of the refraction of these substances, which
he found to be for steel, and for mercury. This
method does not give the quantity OF polarlzed
light but the relative proportion between that
quantity and the total light. To modify the pro-
cess so as to render 1t suitable for that purpose
it is essential TO commence by the graduation OF
the pile of glass plates, In order to ascertain Tor
given incidence what was the quantity of poarlz
ed light which the glass plates neutralized by
causing a completely pearlzed ray to ial on
plate OF rock-crystal perpendicular to It's axis In
such q N amer that the principal section OF the
crystal comedies with the primitive plane OF po
lariZation we have, on turning the plate two INA
ees, VARYING in intensity according to the law OF
the square of the cOsine. but which, from the thin
ness OF the plate entirely superpOse on each other
These tw o images are pOlarlzed IN two perpen-
dicuar planes and form neutral light, Oy their su'
proposition, long the quantity OF light is
equal in the two but if this quantity happens to
vary In either one of the images, the other having
all its light neutrazed, viii leave certain resi-
due of polalized light, which the pile OF glass
plates will entirely obliterate
The green color observed IN light, when 1t IS
obliged to traverse greater thickness OF glass
then ten plates, has prevented NM Arago and
Laneier up 10 the present time from extending
the limits Of their table for representing the guam
titles of polarized light, but they hope that, by
using very transparent glass, having oxide OF ENC
for lis basis which they are at present occupied
in preparing that they shall be able to extend the
table considerably.
This process of polarimetry will allow of our
measuring the quantity OF light reflected and re-
fracted at great angles, which the usual phone
tetric method was always found, by M. Arago in
capable Of affecting.
GEOLOGY ANO MINERALOGY OF EMERY
An extended, able and interesting Memoir on
Emery was presented to the French Academy OF
Sciences during the past Summer, which has been
given TO the public in the November number OF
sulhmans Journal by the author, ]. Lawrence
Smith NJ. d. an American mineraloglst The
general use of the article of Emery in the Arts
and the ordinary pursuits OF life, have led US to
prepare a succinct digest OF Mr.. smith interest
prior 10 the wear 1916, Emery although known
TO exist in many places in greater or less aoun.
dance. was supplied TO the arts from the island OF
Nexos in the Grecian Archipelago, and the pro-
prietors of the mines in that island possessed en-
tire control over the price OF the mineral Inc
Fnerv from Naxos frequently went under the
name of Smyrna Emery, from the fact OF Its com
ING to from that port where it was nally car
ried from the island for future expectation. Frlor
to 1e46 also the existence of Emery was not re-
marked In Asia Minor or any OF the contiguous
islands except that Of SemOs-a TACT alluded 10 IN
Tourneforts Travels in the Seventeenth Century
In the latter part OF $780, Mr. Smith, tue author
Of this paper, arrived in Smyrna, and was SHOWN
specimens which he recognized as Emery coming
from, a Mace twenty miles north of Smyrna; they
had been first discovered through the agency OF
knife grinder of the country, vino had been IN the
habit of using it to charge his wheels me I'M
rortsnce Of this circumstance 70 the IurAlsn uOV'
errment as well as TO the arts Emery being at
that time sold at a most exorbltant ratej INDUCED
MIR s to return to Smyrna in the early pact Oh
1917. for the purpose OF examining the supposed
locality of this mineral. On this second VISIT other
localities were made known, which mad oeen
brought TO light by al English Merchant hsnieu
Healy. " ~, S-;.L !;
racted his ANIMATION was that of GRnauch d0gh,
a mountain about twelve miles east OF the ruins
&C Fpbesus. Before, however, arriving there ne
discovered the mineral imbedded IN cacareous
rock in a valley twenty miles soutn Oh smyrna
called HYqhDdn B0HTgs the position being I'M
favorable for the study of the Geology OF the sub
stance lis route was continued to the place
originally fixed upon The mountain OF Gamuch
was composed Of blnish marble resting on MICA
state and gneiss On the very summit the en-
erv was found scattered about and projecting
above the surface of the soil. Returning TO Con
stsntinople, Mr. made report to the Ottoman
Government and a Commission was soon dis-
patched to examine thoroughly into the impof'
tance of this mine This discovery, unlmportant
In itself has subsequently become OF great value
to secure 70 the enterprisiag American the pr
ority Of the discovery and examination oil Emery
IN sifn in Asia Minor.
The Emery is found in different places IA LUG
NIT three miles from the village OF Gqmacn, anu
some 500 or 600 feet above the level OF the vat
lev. The mineral lies scattered on the surface N
the greatest profusion, in angular fragments .,
! dark color, and large masses OF seversi eu"s
-. go .eer projecting above the surfaces IN