Savannah morning news. [volume] (Savannah) 1868-1887, 1885-03-23

How the "CarbOn Points" are Made
5000 of Them Used in Savannah
Every AIonth-SOme Interesting Facts.
OF the thousands Of people who pass
under the electric light every night, very
few have any idea Of the mechanism
which produces its dazzling bright
ness. The carbon points which are pick
ed up under the lamps and towers, and
which for a long time after the electric
light was introduced in Savannah were
carried around as curiOsities. form one of
the most interesting essentials of the cleo
trio lighting system. A NEWS reporter
was informed yesterday by Supt. heck. IN
charge of the works, that over 5,OOO OF
these carbons or carbon poizts which con-
stitute the candles by which the light Is
produced. are used in Savannah every
month. The process Of their manufacture
is extremely interesting.
When the arc light, which is the system
used in Savannah. came INTO use extern
sfveIv. the basis of all carbOns then made
was the coke remaining in gas retorts
after all the gas and other products had
| been extracted. This material, while in
| many respects excellent, contained more
| or less mineral impurities. the same
/ which constitute the ash which results
| from the combustion Of coal, and the sup
ply was limited. 1t finally occurred 10
I some one that the coke, which is left as
residuum from the final distillatiOn of Pc
I trOleum. was free from any objection on
/ the score Of mineral impurities, and that
| the supply was sufficient for all probable
demand.
At the time that Mr.. Charles f. Brush,
| of Cleveland, Ohio, invented the first
practical system Of arc lighting this pc
| trOleum coke was a waste product of the
| great Standard Oil Works whose distil-
| leries are at Cleveland. and which was at
/ an expense to Get rid Oft.
Examination and analysis showed that
! this petroleum coke contained over SO per
cent pure carbon, and experiments made
with IL showed that the resulting
/ points were superior to anything pre-
viously produced. The petroleum coke,
/ Of which Brush carbOns are made, comes
/ in large Jumps and looks like charred
I spOnges. The material is comparatively
I soft and easily reduced.
/ The process employed in the manuiac-
| ture Of the carbOns, while its details are
a secret Of the Brush Company, is gener-
! ally known by those who have knOwl-
! edge Of electric lighting. The coke is
I first put into a grinder, by which it is
1 crushed into fine pieces. 1t is then placed
l in large iron cylinders in which are
I number of cannon balls. The
q
\ carbon is pulveriZed into exceedingly
! line particles. 1t is then taken from
the s'tumbling barrels" as the cylinders
! are called. and put into a large kettle
I containing tar and heated. The coke is
stirred until 1t becomes nearly dry, and
is then poured into mOulds, each mould
| containing u carbOns. When the mould
is filled it Is placed in a furnace and
| heated. so that the tar again becomes
] fbfc a aurhOnc nrn
/ put into a hydraulic press and subjected
[ 10 an enormous pressure. When the
I pressure Is removed the carbCns are
taken out ready for baking. Some manu-
1 facturers are said 10 use poor mo-
lasses instead of tar, and in fact
any sticky substance will answer the
| purpose, as it is simply used to hold the
carbon fast in place. The next process Is
I the final baking. This is done in furnaces
constructed in about the same way as
those used in rolling mills.
In order TO exclude the air and prevent
| combustion the carhOns are packed in
iron boxes and heavily covered with sand.
| The furnace is heated until its contents
| reach a white heat. AS soon as this is
| reached the fires are eXtinguished and the
| furnace allowed to cool for two DAYS be-
| fore opening it. The iron boxes and their
contents are then removed. The carbOns,
when taken from the boxes, are hard and
] brittle. They are then taken to the
/ plating rOOm," where they are copper
I coated by being placed in long glass jars
containing blue yItriOl and copper plates,
a current from a plating machine being
I so arranged that the current traverses
/ each carbon. which in fifteen minutes re-
I ceiyes a sufficient amount of coating to
make it, with the aid Of the copper coat
I ing, of very little resistance. They are
then given fresh water bath to remove
the acid. and are ready for use.
The carbOns are a very important mat
| ter TO be considered in arc lighting.
. Should the man who attends the furnaces
| allow them to remain too long at
at a white heat, they will be too hard, and
will not give steady light. If they are
not heated enough they Will be too soft,
and will burn too fast, without giving a
I GOOD light.