The New York herald. [volume] (New York [N.Y.]) 1840-1920, 1850-08-26

restT1cted nlmseH 10 a DTleI nouce OF the general
scope and the investigation, committing the larger
body of details, OF which the paper consists to the
published TRANSACTIONS of the association. He re-
marked upon the fundamental importance of the
investigation 10 the great questions of chemical
geology and agriculture, Hitherto, il has, for the
most part, been taken for granted that the water
which penetTates through the soil and the inter-
stices Of rocks, is capable of slowly dissolving
these materials. Iae actual proof of the solvent
power, by laboratory experiments, and the mode
in which it breaks down the cohesion of mineral
masses, by attacking the lime, magAesia, prot0zd
efiron, soda and potash, had never, except in one
or two instances, been distinctly shown. Prof II.
then enumerated list of simple minerals and
rocky masses which had been the subject of ex-
pertinent with pure water and water impregnated
with carb. acid. These included many varieties
of felspar, mica, hornblende, serpentine, epidote
zeolites, NC, well as GRANTEES, sienites, traps,
lavas and other rocks. Each Of these, in line
powder, gave, by the interporacious method of the
tache, unequivocal proof of the solvent action of
the carbonated water, and many of them were dis
timely acted on by pure water. All minerals con-
tanning lime, magnesla, protoXid OF iron, potash,
soda, or hthia, were found subject to this decom-
posing action. Many of them, when in larger
quantity, digested in the liquid, yielded sufficient
amount of solid matter the solvent water 10 ad-
init OF cumulative determination Prof. II. alb
stained from occupying the time of the section
with any further reference TO the results of these
experiments upon rocks and minerals, or with the
similsr ones, by which the presence of alka was
demonstrated in wood, anthracite, bitumnous coal,
&C. lie C0nciuutu ny again ItHldfklnB upon the
very important bearing OF these results upon the
questions connected with the disnegraiion of
rocks, formation of soils, nutrition of plants, and
others.
AFTERNOON SESSIONS.
In the section of Physics and Mathematics at 8
O'clock, the inst communication was Dy Professor
LooMis, of New York University, on optical mo-
wing Of figures. He said, there is an amusing opt-
cal experiment frequently exhibited by means of
u small igure-a mouse, for instance-worked in
led worsied' upon green ground, or worked in
green upon red ground When this figure is mo-
derately illumined by the light of candle and
gently agitated, the mouse appears III motion upon
the canvass. Having met with no explanation of
this experiment, which is entirely satisfactory 10
my mind, have instituted a series OF new expert
ments, in the hope of deducing from them plaus-
bic The oY. The following are few of the eX-
periments -
First. we place red circle of half an inch d.
arneter upon green ground, moderately lllumiaed
by the light OF candle, after directing the of
the eye steadily upon the circle, for few seconds
il appears OF paler red than ordinary; but If we
direct the axis Of The eye little 10 side of the
circle, we see il of deeper red than ordinary. As
often as the axis of the eye returns to the circle, it
appears ale; the momCnt il is throWa oil, the
circle appeeIs of very deep red.
Secondly five place a green circle upon red
ground, WHEN the axis of the eye IL directed upon
n, the circle oprears Of a darker green than ord
nary; but II the axis he turned little to side
it appears Of q brighter green than ordinary. The
dalk gletD ana he iight green may be made to
succeed each ether at pleasure, by slight motion
of the sxs Of the eye. II the axis OF the eye be
thrown ittle above the circle, il appears light ii
il be directed iaiTly upon the circle Il appears OF
daik green; II the axis be thrown little below The
circle, lteppears light.
Third. II the AXIS Of the eye be kept fixed in one
position, end the circle be moved up and d0gn,
then when the circle comedies with The dire cuOn
OF the axis, appears OF dark green; but IN every
othtrposidon, At appears OF light green. IA o.
cillatoiy motion OF the Circle therefore, causes the
appearance Of dark shade ofgreen passing over IL.
Fourth. When the last experiment rs repeated
with a red circle upon green ground, the appear
eIce is that Of light shade of red passing oyerit
tnth. II instead OF q circle we employ hgurc
eta small animal, when the card - agiiated The
appearance is that 81 shadow pasiog over IL, and
we receive the impression Of an animal In motion.
Sixth. liza blue color be substituted Tor green, IN
eech OF the above experiments, the eifecis are
nearly the same. Indeed, certain shades of blue
BDd green cannot be distnc rushed from each oiher
by candlclight Nrmber oas j. thought 10 be the
fUndamentGl experiment from which all the others
naturally follow. Thi. experiment appears 70 be
tolerably well explained, by surprising that the
- loIoIncn ceniraie" IA more sensitive 10 red light
thaa other parts of the reiina. Accordingly, when
the axis Of the eye is turaed directly upon th- red
ciice, % appears dull but II the axis be throwa
lt,le TO one side, the red appears much deeper.
When the axis Of the eye is turned upon the green
circle, It appears daTker-that is, les vivid; bat
when the axis is thrown liuie to ohe SIDE, ne
green appears more brilliant
Seventh. These experiments viii only succeed
with certain combinations Of colOrs. Red must
lie comtincG with green, or blue, OF purple.
Orenae must be comhined with hqb; blue; ggeeu
with red, blue with red. violet with red. C1nsi-
dting that none OF the colors used IN these excu-
mems are Tho pure colOrs O. the spectrum, " -
thought that in each Of these combinations, one OF
the cuoIs Inay be pronounced complimentary 10
the other. The reason why complimentary colors
must be associated, probably, ~ that when me
eye is strongly Impressed win any color, "
becomes particularly sensitive 10 rs complimentary
color. Hence, although we may obtain similar
results wish green circle upon white ground,
the changes Of tilt arc bui slight, and would not
be noticed uulpss particular attention were gwen
20 the experiment. The changes are no. striking
y hen green circle Is placed UPON a red ground.
Why do not these experiments succeed equally
Wen in daylRhi The eye appears 70 be most
sensitive 20 slight chgnves o. thlde when t ~ not
excited by very strong light. Hence these cN-
yeumcnts sed but with "a moderate iuminl
tcn. They do not succ,e ed well IN strong light,
whether II be gashaht or daylight The eye IS
moai sensitive vLtn -crrcped ifom The direct e.,
itcf - ib~ iEAi. era Naf r4pfumrnis succeed
bat when the bach is fufH.t flutr T. The source nt
hGht The effelimruta. therefore. succeed b1t
inoIfi' rtrty " 1en DC hgHt Ceasa from great
number ~ CsndIes in d,a voc r..fs N the room,
Cr homthr q .ig4e .hr @. Day Tie ilrc' OF the
TrCftuce 81 the rl.t iftrUrf.lr I.'. 10 deepening
The tint 81 any of,C'. m. PR .oH1 by Pilcng =
stripe &C green, hsii aa inch 30 Pose dtn, upoa rel
oroynd. The Ceuue OF ing Dsht sppeats mn' a
lighter than the msrV;n. Professor Loomis exhi-
hiitd specimens % the various coinTs worked ~
worted on cards
Pfofsfsei DACuv ystcl Il be bad tired DE cH'e-
rireut ly say odCr means TINA "otHn8 30
worsitdl
FIcfsisor Looa,is said he had, w,.h parsr.
Professor BAcnE--lisye vOu s1ccer3edi
Professor L.OJurs--i have uct
Professor BAcin--Nor l-Odsclic) -ant z
have ined 10 cGen.
PIOi, ssOr Gown mcAtiOlC1 thai he and some
sr members Of H.. association. whfn visitily
tre horse Ct Pro ssOr Norton, The 0'her evcii1r.
were Attracted by the appearance a various co'3f
wolkcd 10 worsil ia iootsiool, which presented
those eiltcts Just dilaied upon.
Professor GIui-, "a New lotk, presented psper
O. he in,iucncc Of tcInpeniuc % the ahs'ution
g.. 3fLL An extended list az suh8iaacrs was pee
fehied, establishing the principle tha, in the case at
those substances which unicrgo changes oi color
upon the application Uf heat without chemical "
rtrnsnebt physical change, the rtffnghihy %
The reflected rays eimiaIhes with The " ieniif,,
or, IN other words. Tho absorption proceeds n CIV
cases, from the violet toward the ted end OF tue
spectrum.
rvrrI.r SESSION