New-York tribune., 1871-09-07
SCIENTIFIC NoZEG

A CRrAr ELECTRO NJ AGNET.-The Stevens
Vn.tuto Of Technology has electromagnet made In
Ansona Conn.,, which weighs about l,eoo pounds, ana
has lifting forcc estimated az between 80 and 20 tuns
About pounds Of copper wire, one NTH OF an ,nSn
1li inches external diameter The cores are hollow, ana
e1rS RchFs Ts IN is about ys aes ne O%eruSs
Nuat used by Ia; alay IN his famous researches
TEST FOR THE PRESENCE OF OzoNE.-M.
aAmy has recently published in Paris journal the re-
eu Of his experiments In obtaining reagents for ozone
lie says that paper moisened with tho oxide Of thaium
when freshly prepared s far more sensitive 70 OZONE
than that prepared with the iodde Of potassium and
starch when RAPID and trustworthy test OF tne pre- =;
theum s recomme nded; but u should be understood
that the seHsrveness q this ressent depends on the
strength Of the solution and the extent to when the oAue
has absorbed carbonic acid
CoLoRs CHANGED BY HEAT.-Prof f. 6. Hous-
con and Elihu Thompson Of the Central Hlgh eonoo
OF Philadelphia have recently made series OF expert
ents to the law by which the color OF various
salts and oxides changed by the action OF obscure
heat rays The substances under examination were
placed In the state Of dry powder strips of sneet
copper which were heated by OF an ordinary Bun
cen burner Coored bodies which did not return 70 tnen
original being cooled were excluded from tue e
pertinent. 1t found that in all cases IN "ncn inc
color OF body Ia changed by the application ot neat,
original color regained on coonng tne ~ ;ba
the body being In no wise altered tne h, censes the
color pass of greater to one Of less msn ~
ss s 81 81 Un of aT number vOets changed by
heat into indgoviOets indgoes ndigoes INTO Dues
green's or yelO9s; yellows into yell9w-oranges, or
oranges oranges into oraIgereds or redS ana nna
OF cold the order is observed In many instances
more colors for example, the green odide Of mercury
nasses from yelloWish green through the yellow and
to s S heat Tf ens
light have rearding effect on the latter and change
that producing the extreme violet have nearly
double the velocity OF those producing dark red.
A STEAM IIYGROMETER.-This instrument is
designed for the purpose of measuring the amount OF
moisture in steam generated in ordinary boilers; the
terms wet steam" and dry steam" being used TO dis
tnguish steam holding particles Of water from that
which has been completely voatilized. The construe
Gon OF this instrument is based the fact that the
Of heat in pound Of water at 22o Fahrenheit
and pound OF steam at the same temperature are well
To determine the Of heat carried out Of
boiler, apparatus has been devised which consists
OF scalc,beam with platform and thcky felted
water-cbamber at end. and eOunterpOise at the
other having sliding weight indicating points and
hHfpOunds. The walls Of the waterchamber are made
Of thin timed sheet copper there being two shells be
cover Is also 'i provded through which IS inserted
rea6 ar b of derrrss eSeS
copper pipe rests upon the inner oor and passes ont at
the steam Induction pipe The lower part of the cham.
Der has the shape Of an inverted tunnel to which is
eoSR an in then the aso s with
cock completes the apparatus. To use this instrument
five pounds Of water placed in the chamber and
raised to so Fahrenheit, by allowing steam to pass
through the coil The surplus water is drawn Of leav
ing hve pounds OF water at 60 containing 400 units OF
heat The sliding weight is then placed at the 81 pounds
notch and the steam to be tested is allowed TO flow in
until the scaebcam Is balanced The influx OF steam Is
then stopped and the thermometer b read With these
data the amount of water In the steam is calculated
THE COsINE GALvANOMBTER-Thisn name has
been given to new form Of gavanOmeter by its In
ventOr John Trowbrdge Assistant Professor OF Physics
At Harvard College The instrument consists OF deli
c magnetic needle, inch and fourtenths In length,
proyided with long aluminium pointers. Tho circular
box in which this needle horizontally attached
TO stationary ring. On the outside Of this ring, by
Of pvOts opposite TO each other Is attached
movable ring u inches in diameter, which wound
the wire conducting the electric current AsemiCrcuar
scale spans the stationary ring and Ia perpendicular to
both the plane and to the plane in which
the needle The movable ring first placed hort
only acted upon by the earth's magnetism; but as IT
s horizontal axis the action Is indicated by
will be proportional to the cOsines Of the inclination OF
che plane Of the current measurng the angle from
vertical line. Careful experiments made with resist
introduced into the current irOm one up 70 zen
ohms show that, with large defections OF the
needle, the ratio Of cOsincs S nearer the ratio
of intensities than the ratio Of the tangente, with
emAer denectOns. The ratio Of the tangents is how
that OF the nteDstes than the ratio OF tile
cosnes With larger deHecons. therefore this instll
appears give closer results than the tangent gal
vanOneer. Moreover, many determinations Of the in
tensy OF the current can be made with the new
instruments by forming table Of the values OF the
cosines of different angles OF VACCINATIONS IN terms OF tne
dehectOns OF the needle which currents OF known
produced when inteIpOsed. III the tangent and
the alvanomeers plane of the needle and that
of the current have fixed relation Consequently only
one determination with each can be made.
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