532 
APPARATUS  FOR  THE  USE  OF  GAS  IN  PHARMACY. 
supporting  vessels  over  it,  and  secures  the  gauze  upon  the  inner 
ring- 
I  have  added  this  contrivance  with  a  view  to  operations  re- 
quiring a  more  elevated  temperature  than  that  furnished  by  the 
combustion  of  the  gas  in  jets  from  the  ring-shaped  burners. 
Being  open  at  the  bottom,  the  furnace  allows  a  free  ingress  of 
air  to  mix  with  the  gas,  which  being  ignited  above  the  diaphragm 
of  wire  gauze,  produces  perfect  combustion  without  the  least 
smoke,  and  with  increased  evolution  of  heat.  The  three  upright 
supports  attached  to  the  outer  ring  will  bear  a  heavy  receiving 
vessel,  and  at  the  right  elevation  from  the  flame  on  the  surface 
of  the  wire  gauze.  # 
This  furnace  may,  of  course,  be  connected  by  flexible  tubing 
with  the  gas  pipe  from  which  it  is  supplied,  and  may  be  moved 
about  on  the  counter  or  floor.  Ordinary  gum  elastic  hose  may 
be  very  well  slipped  over  the  lateral  pipe  and  on  to  an  ordinary 
burner,  without  any  metallic  connections,  ground  burner,  or 
mercury  cup,  the  flow  of  gas  being  regulated  by  the  stop-cock 
on  the  permanent  gas  fixture  to  which  it  is  attached.  The  con- 
sumption of  gas  by  this  burner  under  ordinary  circumstances  of 
pressure,  with  a  full  head  turned  on,  is  from  seven  to  ten  cubic 
feet  per  hour,  though  this  head  will  smoke  without  the  use  of 
the  wire  gauze  attachment ;  for  evaporation,  without  the  attach- 
ment, a  much  smaller  consumption  is  required.  An  idea  of  the 
heating  capacity  of  the  full  head  may  be  gained  from  the  fact 
that  a  gallon  of  water  in  a  pharmaceutical  still  of  tinned  iron, 
placed  on  the  projecting  arms  over  the  wire  gauze,  was  raised 
to  the  boiling  point  in  thirteen  minutes,  though  in  an  uncovered 
enamelled  iron  vessel  it  required  near  twenty  minutes. 
One  advantage  from  the  use  of  this  furnace,  without  the  wire 
gauze  attachment,  for  operations  requiring  a  low  heat,  is  that 
the  jets  are  not  materially  affected  by  the  wind,  which  on  a  sur- 
face of  wire  gauze  is  apt  to  blow  out  the  flame  whenever  much 
reduced.  The  cast  iron  rings  are  also  an  improvement  on  com- 
mon methods  of  adjusting,  securing,  and  renewing  the  gauze ; 
no  tripod  is  necessary  for  supporting  the  vessel  to  be  heated, 
either  with  or  without  the  wire  gauze  arrangement,  and  the 
strength  and  durability  of  the  whole  apparatus  recommend  it 
above  the  ordinary  iron,  tin,  or  even  copper  cylinders. 
