The  essential  apparatus  of  candle-manufacture  are  shown  in
Fig.  179,  which  is  a  view  of  a  plant  for  large-size  candles,  showing
steam-boiler,  aluminum  jacketed  melting-kettle,  and  candle-machine,
with  suitable  water  and  steam  connections;  also  a  tin  pouring-
bucket.
On  pages  505  and  506  are  shown  methods  of  setting  up,  piping,
and  filling  the  candle-machines  and  of  removing  the  racks  of  candles.
These  methods  naturally  vary  with  each  establishment  and  for  which
no  hard-and-fast  rule  can  be  made.  Fig.  182  is  of  especial  interest
in  that  there  is  shown  a  plan  of  the  actual  equipment  of  a  combined
soap-  and  candle-plant.
Melting-kettle.  —  The  melting- kettle  may  be  heated  either  by
steam  or  direct  fire,  but  preferably  by  the  former.  All  parts  in
contact  with  melted  material  should  be  non-corrosive,  so  as  to  avoid
discoloration  of  the  candle-stock.  For  this  purpose  steam-jacketed
kettles  lined  with  aluminum  give  the  best  satisfaction,  as  this  metal  is
light,  durable,  and  not  affected  by  the  acids.
