326 
ILLUMINATING  GAS  FROM  PETROLEUM. 
albuminates  decrease  in  all  the  organs  towards  autumn  ;  but  if 
the  dry  substance  of  the  entire  plant  is  taken  in  consideration, 
their  absolute  quantity  is  increased. 
J.  M.  M. 
ILLUMINATING  GAS  FROM  PETROLEUM. 
By.  C.  a.  Martius. 
The  very  low  price  of  petroleum  has  caused  many  experiments 
to  be  made  to  utilize  it  for  the  production  of  illuminating  gas. 
This  has  been  best  accomplished  by  Hirzel,  of  Leipzic,  who  uses 
crude  petroleum,  or  preferably  the  residues  left  on  the  rectifica- 
tion of  the  crude  oil,  which  may  be  obtained  at  a  low  price.* 
The  gas  is  produced  by  conducting  the  oil  from  a  reservoir 
through  a  tube  in  a  uniform  current  into  a  red  hot  retort ;  the 
gases  pass  through  an  ascending  tube,  a  receiver  and  a  condenser 
filled  with  bricks  into  the  gasometer.  The  process  is  very  sim- 
ple and  devoid  of  danger.  About  200  cubic  feet  of  gas  are  ob- 
tained in  an  hour.  An  obstruction  in  the  tubes  does  not  occur, 
but  after  some  time  the  retort  must  be  opened  and  the  coke 
raked  out. 
This  is  undoubtedly  the  purest  illuminating  gas,  and  consists 
only  of  carbohydrogens,  which  are  not  condensed  by  cold  or 
pressure,  and  may  be  kept  without  alteration  and  without  losing 
its  illuminating  power.  Neither  oil  nor  tar  is  separated  in  the 
pipes,  and  the  gas  is  free  from  carbonic  acid,  sulphurous  and 
ammoniacal  compounds,  so  that  it  may  be  collected  in  the  gaso- 
meter without  undergoing  any  purification. 
It  is  remarkable  for  its  high  specific  gravity,  =  0*698  (coal 
gas  =  0-42)  and  its  great  illuminating  power,  which  is  four  and 
and  a  half  to  fi\^e  times  greater  than  that  of  ordinary  coal  gas, 
so  that  burners  may  be  used  which  consume  only  three-fourths 
to  at  most  one  and  a  half  cubic  feet  per  hour. 
It  has  a  peculiar  odor,  so  that  leaks  in  the  pipes  may  be 
readily  discovered  ;  but  the  odor,  which  reminds  of  acetylen,  is 
difi"erent  from  and  less  disagreeable  than  that  of  coal  gas.  Ace- 
tylen is  present  in  this  gas  in  such  proportion  that  the  acetylen- 
*Hirzers  gas  apparatus  is  figured  and  described  in  the  American 
Eugiueer  of  June  18,  1870,  published  by  Evans  &  Co.,  Philada. 
