The Salt Lake herald. [volume] (Salt Lake City [Utah]) 1870-1909, 1895-10-20
ELECTRICAL NOTES

The following comparison. due "a p
lez. will be useful to electrical engineers
IN presenting the advantages Of electric
H$htlng from the standpoint of cooInass
Inc tSures quoted are relative to
given quantity of light: Arc light. 4. in
candescent light, II; kerosene. argand
burner, S3l; gas, argand burner. $50
candle. 473; gas, butterfly burner. 511
Inc neat question is very important
one but 1t is as nothing compared with
the question of vitiated atmosphere. In
inns respect. of course, electricity com
pares still more favorably with all other
sources of artificial light.
In paper read before the ROYAL So
clety ON the effect Of pressure Of the
surrounding gas on the temperature of
tne crater of an electric arc light. Nr.
w. h. Wilson states that of late wears
IL mas often been assumed that the tenn
perature of the crater forming the r,o.si
tive pole of the electric arc is that OF
DOlllng carbon. The most modern deter
mutations give that point as about 3G1
degrees to $500 degrees G. In order to in
EeSugdte whether increased pressure in
the gas surrounding the electric arc would
raise the temperature of the crater ne
used strong caSt-irOn box, in the in
terror OF which an electric arc light
could be maintained. BY increasing the
pressure of the gas in the box the tenn
Derature Of the crater is considerably
lowered instead of being raised and the
experiments seem to show that the tenn
perature of the crater, like that Of a
hlament in an incaudeScent lamp, de-
ponds on how much it is cooled by the
surrounding atmosphere. That carbon VO-
latluZeS in some form at comparatively
low temperatures seems likely from the
way in which the carbon of incandeS-
cent lamp tilaments is transferred to
the glass. The pressure of the VapOr OF
19c
very small, and further it would seem
that the supposition is not borne out by
these experiments, and that carbon may
exist there IN the solid form al very !
high temperatures although the pres
sureS are comparatively low.
In two pole dynamOs the proportions OF
ring armatures vary from a length equal
to One-half the diameter 10 a length
equal to one and One-h2If diameters. IL
is common to make the length equal to
the diameter. For drum armatures the
one-half diameters and sometimes three
diameters. 1t is common to find the
length equal to two diameters.
Gutta percha heated in hot water at
about 100 degrees + becomes plastic. and
will take a fine impression with slight
pressure. When guttd percha is soaked
for few hours in benZOle or naphtha.
it becomes swollen, and if it is then dip
ped in hot water it becomes 50 plastic
that it may be used with safety on very
fragile and delicate objects. Specially
adapted to electrOtyping.
The cotton thread used for the fla
ments of incandescent lamps is parch-
mentized before carbonization by pass
ing it slowly through a solution of sui
phuric acid two parts. water one part.
and finally washing it in water until
every particle of the acid is removed.
The parchmentized thread. after drying.
is reduced to a uniform diameter by
drawing it through dies, after the man
ner of wire drawing.
A thermopile. for experimental pur-
poses, may be made of pieces of German
silver and copper wire, twisted and
hard soldered at the ends. forming ser.
les of pairs, and arranging the wire3
pointed star so that the German silver
and copper wires alternate. the ends OF
the series being left unconnected. The
inner points of the star are heated over
a kerosene lamp. The wires may be No
16 and six inches long.