532 
HISTOEY  OF  PETROLEUM  OR  ROCK  OIL. 
bution  throughout  a  considerable  region  in  the  adjacent  portions 
of  New  York,  Pennsylvania,  and  Ohio,  it  is  only  in  a  few  dis- 
tricts that  it  has  been  found  in  quantities  sufficient  to  be  wrought 
with  profit.  The  wells  of  Mecca  in  Trumbull  County,  Ohio, 
have  been  sunk  from  30  to  200  feet  in  a  sandstone  which  is  sat- 
urated with  oil;  of  200  wells  which  have  been  bored,  according 
to  Dr.  Newberry,  a  dozen  or  more  are  successfully  wrought,  and 
yield  from  five  to  twenty  barrels  a-day.  The  wells  of  Titus- 
ville,  on  Oil  Creek,  Pennsylvania,  vary  in  depth  from  70  to  300 
feet,  and  the  petroleum  is  met  with  throughout.  The  oil  from 
different  localities  varies  considerably  in  color  and  thickness, 
and  in  its  specific  gravity,  which  ranges  from  28°  to  40°  B. 
(from  -890  to  -830.) 
The  Valley  of  the  Little  Kenawha,  in  Virginia,  which  is  to 
be  looked  upon  as  an  extension  of  the  same  oil-bearing  region, 
contains  petroleum  springs,  which,  so  long  as  1836,  according 
to  Dr.  Hildreth,  yielded  from  fifty  to  a  hundred  barrels  yearly. 
It  here  rises  through  the  carboniferous  strata,  and,  as 
elsewhere,  is  accompanied  by  great  quantities  of  inflammable 
gas. 
The  black  inflammable  shales  of  the  Devonian  series  in 
Western  Canada,  which  were  formerly  referred  to  the  Hamilton 
group,  and  are  now  considered  to  belong  to  the  base  of  the  over- 
lying Portage  and  Chemung,  appear  at  Kettle  Point,  on  Lake 
Huron,  and  in  portions  of  the  region  southward  to  Lake  Erie  ; 
but  the  oil  wells  sunk  in  Enniskillen  show  that  the  source  of 
the  oil  is  really  below  the  horizon  of  these  shales,  inasmuch  as 
the  underlying  argillaceous  shales  and  limestones  of  the  Hamil- 
ton group  are  there  found  near  the  surface,  and  have  been  pen- 
etrated 120  feet,  at  which  depth  oil  is  still  met  with,  leaving  but 
little  doubt  that  it  is  derived  from  the  limestones  beneath,  which, 
both  in  New  York  and  in  Canada,  are  impregnated  with  petro- 
leum. A  somewhat  slaty,  brownish-black,  bituminous  dolomite, 
belonging  to  the  Corniferous  limestone  from  Pine  Creek,  near 
Alma,  in  Kincardine,  gave  me  not  less  than  12-8  per  cent,  of 
bitumen,  fusible  and  readily  soluble  in  benzole,  and  another  from 
the  Grand  Manitoulin  Island,  which  was  a  brown,  crystalline 
dolomite,  yielded  from  7-4  to  8*8  per  cent,  of  similar  bitumen. 
The  solid  form  of  this  bitumen  at  the  outcrop  of  the  rocks  is 
probably  due  to  the  action  of  the  air. 
