234  Conservation  and  Cheinical  Engineer,  j AmMayUi*9f0harm' 
and  extend  the  scope  of  the  industry,  to  maintain  and  add  to  its 
remunerative  character,  and  to  give  it  stability  and  promise  of 
permanence. 
Let  us  illustrate  this  view  by  examples,  and  take  first  the  great 
petroleum  industry  to  which  reference  has  already  been  made  in 
speaking  of  the  era  of  exploration  when  the  petroleum  fields  were 
first  outlined  by  the  work  of  the  prospector  and  driller.  The  second 
stage  of  exploitation  began  to  draw  upon  the  help  of  those  who  were 
chemical  engineers,  in  fact  if  not  by  title.  The  development  of  the 
distilling  and  refining  processes  came  first.  Starting  with  the  old 
cheese-box  still  with  its  circle  of  heating  grates  under  it,  there  was 
a  change,  following  upon  the  discovery  of  the  "  cracking  process  " 
as  applied  to  crude  oil,  to  the  present  form  of  cylindrical  still  with 
its  movable  cover  to  regulate  the  chilling  of  the  vapors  during  the 
latter  part  of  the  operation.  This  simple  feature  in  distilling  enables 
the  refiners  to  get  75  per  cent,  or  more  of  burning  oil  from  the  crude 
petroleum  instead  of  the  45  per  cent,  of  a  normal  fractional  distilla- 
tion, while  producing  a  residuum  which  can  be  advantageously  dis- 
tilled for  paraffin  oils. 
The  proper  control  of  the  acid  and  alkali  treatment  of  the  crude 
distillates,  the  change  from  the  old  forms  of  presses  for  paraffin  scale 
to  the  modern  filter  press,  the  introduction  of  bone-black  filtration 
for  reduced  oils  and  residuums  all  contributed  to  develop  and  ex- 
pand enormously  the  several  parts  of  the  industry  to  which  they 
were  applied.  With  these  improvements  in  large  scale  methods 
went  the  inauguration  of  improved  testing  and  analytical  methods, 
so  that  uniformity  of  product  so  essential  for  sound  business  develop- 
ment was  secured. 
Let  us  turn  now  to  the  newer  evidence  of  the  work  of  the  chemi- 
cal engineer  in  the  way  of  conservation  as  illustrated  in  this  same 
industry.  The  collection  and  utilization  for  fuel  purposes  of  the 
uncondensed  gas  from  the  distillation  of  crude  oil  is  one  of  the 
important  economies  that  has  been  generally  adopted.  The  working 
up  of  the  sludge-acid  and  recovery  of  not  only  sulphuric  acid  but 
of  valuable  side-products  is  now  a  feature  of  the  larger  refineries. 
The  introduction  of  clay  filtration  to  improve  the  quality  of  the 
heavier  grades  of  oils  is  an  important  advance  as  well  as  a  step  of 
economy.  The  production  of  gas  oils  from  the  less  valuable  crude  oils 
has  also  become  an  important  industry,  as  these  are  of  great  value 
for  gas-making  and  gas-enriching.    The  more  thorough  utilization 
