New-York tribune., 1875-12-11
APPLIED SCTENCE.

dered non-lumnous by the introduction of gases in
different to combustion, in place Of air. have been
modified by Wibcl IN such a way TO permit the
heating of the mixed gases at the moment Of cOmbus
tion. The diluting gas was introduced through
class tube sodered into one of the dr1ught-holes Of
an ordinary unsen burner, the Others being closed.
and the mixed gases were burned from a platinum
tube readily formed by rolling piece of thin plati-
mum foil spirally, slipped into the top OF the burner
Two opposite horizontal Bunsen burners were ar
ranged for heating this tube Upon heating it when
the flame was rendered non-luminous by air, a. in
the ordinary Bunscn burner or by carbOnc acid,
nitrogen OF hydrogen, Wibel noticed the I'M
mediate formation of a luminous cone IN the in
terror of the flame, which gradually disappeared
when the heating burners were removed. The
temperature required was not very high, especially
If the gases were mixed in the proper proportions.
The dame did not strike down. and III all respects
resembled an ordinary luminous name alolthng
decomposition took place IN the hot tube with nitro
gen and carbonic acid as ascertaned by analysis of
cas- taken from the tame by ASPIRATION, ts wen ~
from the exceedingly 81 ght deposit OF carbon IN the
tube sheet-iron plate, perforated so as to ut the
burner prev ented the products OF combustion from
the heating burners from coating the Hamt, IL was
also found that when the llancs OF Two good bsen
burners were brought IN contact WIN the exterior
mantle of hane rendsHed n0n-lumlnOus by ear,
bonc acid, an interior luminous cone was formed
which disappeared Immediately on Their removal
tie concludes from his eApfIDltuiS tIll llit nun
luminous character OF the iame IN knapps expert
ment is not due to dllutlon OF the burning gas,
and according 10 the views OF tranNiand or OF
BlOckmann, but rather 70 cooling OF lhe interior
of the flame by the gas inlrOduced-a view that Is
supported by the peculiartlcS OF the fiaine when
oxygen is the dilutng gas. The LUMINOSITY OF the
1ame of substance containing carbon, other things
being equal depends upon the existence ot tenn
perature in the interior which renders possible the
processes of chemical decomposition and comDlna-
iion from which the luminous body proper results
IN ordinary the more or less cold gases formed
from the Illuminating material TIshhg up rom pr-
meath are heated sufficiently by the temperature
developed in the exterior zone of combustion to
produce the change necessary to luminosity.
THE TEMrERATURE OF THE EAIIH-lhe interest
which attaches to careful observations of the tenn
perature Of the earth suggests that the apparatus
which is used in Germany should be better known
in this country in order that, when practicable, it
may be- introduced here The following is a descrip-
ton of it as used by observers in Hungary. In its
general outlines it does not differ from that recon-
mended by Lamont. 1t consists principally of rec
tangular tube buried permanently in the earth,
within which five rectangular pTisms of wood are
placed, one above the otn,r, at different depths Ill
the ground, and which, by simple arrangement
can be easily and Ocbly drawn up. Each OF these
tubes contains thermometer, and there Is hole IN
the side of the main tube opposite 10 the bub ot the
thermometer where the woodwork IS cut away and
the opening closed by plate of thin sheet copper
whose temperature may be presumed to be the same
s that Of the adjacent ground lhc depths at when
the thermometers bulbs remain are 4 = II, lO aid
20 feet. Shenzl, the result of obser' atons made
during eight years, finds that the time required Tor
heat penetrate to depth OF one meter Is on the
average, u days.
The EVAPORATION FROM THE SKINS OF Fruit
BY comparing the evaporation from apples with and
without their outer skins, just has arrived at the
following conclusions: o. The resistance which the
skin offers 10 evaporation is quite energetic at low
temperatures, but diminlshes sensby above the
temperature of 46o until il becomes barely sensible
10 IA 6 x~t.rff,s
formed from the dried exterior cells which opposes
rapid evaporation. l3.l This exterior covering IL
lOrmed gradually, SD that its retardng INFLUENCE IS
scarcely felt for the first - hours, during which
time evaporation continues very rapid. e. SIM
liar covering OF dried cells forms IN the case OF un
pared apples, only after the exterior layer OF cells
has dried up very much. Tie application Of these
results to preparing dried apples shows that for their
rapid production in the best condition they must be
dried at low temperature as possible after hay-
lng been pared.
MOISTURE IN TIE AIR AND INTENSITY OF FRIC-
uONAL ELECTRICITY.-Certan theoretical cOnsid-
eraions having led Rossetti 10 the conclusion that
Ohu's law should apply to frctional as well as to
gayanic electricity, he has instituted experiments
showing that, under similar conditions and III the
same series Of experiments the intensity of the cur
rent nearly proportional to the velocity of the TO-
tation Of the disk OF Holtz machine. This relation
Is influenced by the moisture Of the air in such a
way that the number Of turns which the disk must
make, in order 10 give rise to stream of "a certain
Intensity, Is greater IN moist than IN dry ainos-
pherc. The quantity of WORK which must be eX-.
pended for the development of electricity l. exactly
oporloual to the intensity of the current there
lore. the ratio between the work expended and the
resulting intensity of the current is the same with
increasing moisture.
THE ELASTICITY OF PURIFIED AIR.-SOme re-
searches of Mendeeh and KirpitschOif show that
the product of any volume of air by its pressure.
which according to the law of Maruotte should be
constant for all pFessures is not for the air vary
I = -. 4. l. =.
small quantity as half mlllimetcr. This product
in fact which for perfect gases is constant varies
rapidly in the Of air. The deVidtlOns from tho
law of MaTriOtte for nrcfed air are contrary 10
those observed by Regnaut for compressed air. In
fact, the product Increases when the pressure M
crcaScs. and dmlnlshcS when tie pressure dlmlu-
ishes. These disturbances are far larger than the
possible errors OF observation.
THE ACTION OF LIGHT on CWOROPHYIL-FrOm
a number Of experiments upon the action of light
upon chlorophyll, Wesner has attempted to deter
mine whether the formation of this substance de-
pcnds upon the brightness the absorption of the
light. His observations show that the rate of forma
ton of chorophyl is, for rays of given intensity,
dependent gpOn thelr index of rciractlon. The red
rays between and do not possess the greatest
power of decomposing chlorophyll; but both the
decomposition and formation of that substance pro-
ceed most rapidly under the influence OF the bright
est rays while all portions OF tire visible spectrum
have some power TO produce these changes.
CONDUCTlON OF HAT BY BUILDING MATERIALS
The coetGcicnt Of conductOn for heat of various
building materials has lately been carefully nyesti
gated by Lang, who in his studies. has endeayorcd
to exclude the influence Of radiation. and has made
| measurements 10y means of the thermo-electrc null
tiplier lie finds that the stones considered by him
! are much better conductors OF heat when wet than
when dry, and that various classes OF stones. such
! rs marble sandstone granite. Ac., have approx
| matcly the same COeficients of CONJUNCTION, while
bricks OF all kinds are much worse conductors than
| the natural stones
1nE Proper TINE FOR CUTTING TGEEs.-An eX-
J louh aIa IN Ia