Ao'ctS;  1915™'}  Contributions  to  Industrial  Chemistry.  467 
by  the  blowing  of  hot  oil  residuums  generally,  according  to  either 
the  Byerley  or  the  Culmer  patents,  followed,  and  it  is  now  pos- 
sible to  get,  in  this  way,  solid  products  of  every  grade  of  duc- 
tility and  penetration  and  a  wide  range  of  melting-point  which 
find  a  great  variety  of  uses.  - 
It  must  not  be  overlooked  that  the  industry  owes  much  also  to 
the  engineering  ability  of  the  men  connected  with  its  early  develop- 
ment. The  enormous  extent  of  the  producing  field  would  have 
made  the  question  of  the  transportation  very  serious  had  not  the 
tank  car  and  the  pipe-line  soon  developed  to  relieve  them.  These 
were  the  fruit  of  American  invention,  while  the  Russian  oil  indus- 
try is  to  be  credited  with  the  introduction  of  the  oil-tank  steamer 
now  in  general  use. 
I  have  referred  to  the  early  use  of  "  cracking,"  as  practised  in 
the  handling  of  the  crude  oil  stills  of  most  refineries  in  order  to 
increase  the  burning  oil  fraction  at  the  expense  of  the  heavy  oils. 
This  has  been  followed  by  efforts  to  increase  notably  the  gasoline 
or  light  naphtha  percentage,  which  in  recent  years  has  become  more 
important  and  commands  a  higher  price  than  the  burning  oil.  In 
place  of  the  cracking  by  causing  condensed  heavy  vapors  to  drop 
back  upon  a  superheated  oil  layer  in  the  still,  but  working  under 
normal  pressure,  which  involves  much  waste  by  formation  of  uncon- 
densable  gas  and  separation  of  carbon,  recourse  was  had  to  dis- 
tillation under  pressure,  as  in  the  Burton  process,  now  largely  used 
by  the  Standard  Oil  Company  in  several  of  its  largest  refineries  and 
with  a  considerable  measure  of  success.  Still  more  recently  the 
principle  of  distillation  under  heavy  pressure  and  at  higher  tem- 
peratures has  been  brilliantly  applied  by  Dr.  Rittman,  with  the 
result  of  the  production  of  large  amounts  of  gasoline  or,  at  higher 
pressures,  of  benzene  and  toluene  (aromatic  hydrocarbons)  in  notable 
amount.  This  process  is  now  being  given  a  large-scale  experimental 
trial  by  the  i£tna  Chemical  Company,  of  Pittsburgh. 
A  somewhat  similar  process  of  decomposition  of  petroleum  by 
heating  under  very  high  pressure  has  been  described  in  outline  by 
Walter  O.  Snelling,  but  the  full  account  of  the  method  and  results 
has  not  as  yet  been  published. 
Radically  different  from  these  processes  of  cracking  under  pres- 
sure is  the  recently-described  process  of  McAfee,  who  utilizes  the 
Friedel  and  Crafts  reaction  with  anhydrous  aluminum  chloride  and, 
after  getting  off  the  normally  present  gasoline  and  kerosene,  runs  the 
