Richmond dispatch. [volume] (Richmond, Va.) 1884-1903, 1898-08-28
THE ELECTRIC FURNACE.
4 Wonderful Concentration of Hea'
In n Narrow Compass.
(BOstOn franscriptJ

Boston Transcript
Professor John TrOwbridge. Writing
about the electric furnace, says: There
have been three distinct eras in the prac-
teal applications Of electricity. The trst
was characterized by it's use in tele-
graphy the second by ITS appncdton 10
lighting. and the third by its employ
ment i'm the transmission Of power. We
are now entering upon a fourth era, IN
which electricity may be salu 10 pay
back its debt 10 the energy Whlch pro-
duces il by generating heat IN the elec-
trio furnace. ,,-....,
lutionized certain processes In the arts
The heat Of the furnace is generated by
m electric arc such as we see In the case
IF the arc lights on our city streets. MS
arc is produced BY a current OF electricity
dowing through the acknowledged ar
between two pieces OF carbon. The fur-
mace consists Of a box or paralleloplpeu
1f limestone, having cavity OF slIIIllat
shane cut into II. The electric current
ie ted into the cavity by means Of pieces,
terminals or electrodes. as they are tech
nically called. of hard carbon, which pass
through holes cut in opposite sldes OF the
cavity. Then the oxide or the meidl
which one desires 10 fuse Is mixed with
carbon powder and is packed around The
carbon terminals and is reduced by the
Great heat developed by the VOltaic arc,
produced by the electric current noWlhg
through the cavity from one carbon ter
Is produced. and I'm a similar way carbide
NJ lime which, on being dropped into
water. gives forth the gas acetylene In
great quantity.
For scientific experimentation. the cavity
holds n small crucible which is composed
~ a mixture of carbon and magnesia.
In this crucible are placed the substances
which are 10 be melted. There is no metal
which has not been fused by this FUR
mace Even platinum and iridium, botn
In coli I'm
mace such as had hitherto been used,
melt like wax I'm the electric furnace.
Sometimes a carbon tube is fixed in the
latter furnace across the line Of direction
Of the carbon terminals, or. in other
words at right angles to them, and so
placed that il is about One-half an inch
below the. intense VOltaic arc and about
the same distance from the bottom OF
the limestone cavity. In this carbon tube
are placed the substances which are to be
heated Material can be introduced into
! one end of this tube, and after il is heated
can be drawn of by tipping the tube,
without stopping the current In the fur
mace.
In order TO produce diamonds. iron IS
melted with a large quantity OF carbon
| DOWder and when the mixture has attain
ed a high temperature--oYer 500 degrees
| Fahrenheit-it IL suddenly plunged into
| cold water or a bath OF molten lead. The
lead being a better conductor OF heat
| than cold water. more suddenly deprives
| the mixture Of its heat. on examining
| the Stag small. cOlOrless crystals of car
bon are fosnd. which are Identical I'm their
| properties with natural diamonds.
The electric furnace has the great ad-
| vantage over other furnaces In its power
| 10 localiZe the heat in narrow compass,
and the amount of heat we can pro-
| duce In such a furnace is almost unilmit-
| ed An amount or neat energy equlVaie, l
| 70 700-horse power has been produced In
! an electric furnace cavity which was not
| larger than an ordinary tumbler OF water.
| Sometimes a powerful magnet Is used
| TO direct the electric arc upon certain
| REGION I'm the furnace. magnet has
| The nroperty Of attracting or repellng an
! electrical current. and the voltaic arc In
! the furnace is such an electrical current.
| with such an arrangement-namelN, a
| voltaic arc and a magnet, we have prac-
| 'icaiiv powerful blOwpipe which melts
| lass and the metals like wax and vapor-
| Yes the lime walls Of the furnace. There
| IRE a number of electric furnaces at Ma
| cara Falls. which are used 10 reduce the
oxides of metals ana 10 FORM Such sun
| stances as carbide Of lime. from Whch
! acetvlene * generated. and corundum
| which is used as grinding agent IN the
/ arts. - - al,
tained bv the electric furnace is not fal
! S,ou O.0 degrees Fahrenheit Since al
| Substances which are available for makinl
/ thermometers are melted by such neat
| the question naturally arises, how car
We measure such high temperatures II
/ must be confessed that we cannot mea
| silre A. accurately and can only form az
/ estimate. This estimate can be made By
| electrical means. Suppose that mea
| eured quantity Of electricity IL sem
| through a thin strip Of platinum or Ma
| n,ent similar 10 that In an Edison lamp
| Tbe heat given ont by the glowing pla
| tirum or carbon filament depends upOI
! I'VE quantity Of electricity which we car
| Sorce through IT, We can measure this
! ruantitv very accurately and from IL de
| ,srmine the amount OF heat given on
! -, the 6lament. We know that a stril
~ plotinup red-hot has temperature n
| he neiahb0-hood of laO degrees Fab
! ,n,bei, and when IL Is white hot tempe
ro,n,e Of 3. 400 degrees Suppose that w
Ion the platinum strip red-hot by ;
| hnawn current OF electricity and put
| Tsiicote thermometer al distance o
! -. ar four feet from the strip and rea'
| a. {ndtcation We will then expose tn
sa,,s thermometer 10 an electric arc lamp
s'hich represents the electric furnace
and move IL until II reads the same as
| ala when II was exposed 70 the red-ho
| 10 ,,num strip. We shall md that W
pnust move the thermometer much fur
Tier from the electric furnace, and thu
| Lnou,ing the temperature OF tho red-ho
strin and the relative distances, we cal
| ascertain approximately the temperatur
! OF the electric furnace.