Am.  Jour.  Pharm. 
July,  1 9 17. 
Production  of  Hydrogen. 
317 
the  retorts  are  destroyed  by  fire  after  being  a  short  time  in  operation 
(about  six  weeks)  besides  being  choked  by  the  ore. 
In  a  large  installation  now  in  operation  every  charge  for  the  32 
retorts  for  two  furnaces  with  a  capacity  of  100  cubic  meters  costs 
about  $3,000. 
As  these  retorts  produce  100,000  cubic  meters  before  being  ren- 
dered useless  by  fire,  one  cubic  meter  of  hydrogen  costs  for  the  re- 
placing of  retorts  alone  $3,000-^-100,000  =  3  cents.  Apart  from 
the  high  cost  of  production  involved  in  the  production  of  hydrogen 
by  the  retort  method,  other  drawbacks,  such  as  continuous  repairs, 
loss  of  hydrogen  by  waste,  interruption  of  operating  plant,  ex- 
cessive, unbearable  heat,  and  early  destruction  of  the  furnaces  are 
so  serious  that  the  system  is  not  to  be  recommended. 
The  mere  fact  of  the  imperfect  preparedness  for  operation 
makes  it  unsuitable  for  airship  purposes,  as  the  furnaces  have  to  be 
heated  gradually  for  several  days  before  they  begin  to  produce  gas. 
The  heating  of  the  retort  furnaces  entails  the  use  of  a  special  sys- 
tem of  coke  firing,  built  in  the  retort  furnaces,  and  involves  the  use 
of  a  considerable  amount  of  coke  (about  1,200  to  1,500  kilos  per 
furnace  daily). 
The  oldest  system  employed  by  Giffard,  already  referred  to,  un- 
doubtedly possessed  important  advantages  over  this  system,,  but  the 
difficulty  of  heating  was  a  very  serious  one,  as  is  shown  by  the  above 
mentioned  extracts  from  the  patent  literature  on  the  subject. 
Recently,  however,  after  exhaustive  experiments  many  of  the 
difficulties  connected  with  the  rational  carrying  out  of  the  iron  con- 
tact method  in  large  industrial  plants  have  been  to  a  great  extent 
overcome  by  the  vertical  cylinder  process  and  installations. 
The  method  has  now  been  so  much  improved  by  the  application 
of  entirely  new  principles  that  it  meets  to  a  certain  extent  the  re- 
quirements of  a  process  adapted  to  large  installations,  such  as  rapid- 
ity in  getting  the  plant  into  working  order,  more  certainty  of  opera- 
tion, and  simplicity.  The  vertical  cylinder  generator  is  distin- 
guished by  separate  heating  and  contact  chambers  communicating 
with  each  other.  The  former  serve  for  the  uniform  heating  of  the 
contact  mass,  as  well  as  for  the  super-heating  of  the  steam.  The 
heating  takes  place  at  intervals,  yet  it  is  continuous,  because  when 
the  heating  is  discontinued,  the  super-heating  maintains  the  tem- 
perature of  the  contact  chamber  by  its  radiation  and  continues  to 
heat  the  contact  mass. 
