456  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,  1904.        I  bull.  260. 
(0.8860)  was  priced  at  40  cents  a  barrel  below  that  testing  32°. 
Strangely,  the  company  has  not  increased  the  price  for  oils  above  32°, 
although  much  of  the  oil  tests  considerably  higher.  Oil  from  the  Bol- 
ton region  varies  slightly  from  well  to  well,  but  ranges  about  34°  B. 
(0.8536).  Neodesha  oil  in  general  runs  about  36°  B.  (0.8433),  while 
oil  from  the  eastern  part  of  Montgomery  County,  around  Cherryvale 
and  Coffeyville,  is  variable,  some  of  it  being  heavy  enough  to  fall 
below  30°  B.  (0.8750).  The  readjustment  of  prices  practically 
amounted  to  a  very  appreciable  reduction  in  the  total  amount  of 
money  paid  for  Kansas  oil. 
It  is  found  that  by  the  evaporation  of  its  lighter  volatiles  oil  stand- 
ing in  an  open  tank  decreases  in  gravity  at  an  average  of  one  degree 
a  week  for  the  first  few  weeks,  thus  causing  a  discount  of  about  10 
cents  per  barrel  a  week.  One  test  recently  made  with  oil  fresh  from 
the  pump  showed  a  loss  of  more  than  7.3°  in  three  months.  The 
evaporation  is  much  greater  in  dry  or  warm  than  in  wet  or  cold 
weather.  This  loss  probably  accounts  for  the  fact  that  the  oil  in 
many  instances  tests  below  the  expectations  of  the  producer,  who 
nearly  everywhere  uses  open  tanks,  usually  wooden  ones,  without  a 
protecting  cover.  The  Standard  Oil  Company  avoids  this  great  loss 
as  far  as  possible  by  making  its  tanks  practically  air-tight  and  closing 
them  immediately  after  they  are  filled. 
Prices  paid  by  the  Standard  Oil  Company  for  Kansas  oil,  as  com- 
pared with  other  American  oils,  are  shown  in  the  following  table, 
which  is  the  market  quotation  for  Monday,  December  5,  1904 : 
Prices  of  Kansas  oil,  Decrmhcr  5,  190Jf. 
Pennsylvania    $1.  CO 
Tiona    1.75 
Corning 1.  37 
New  Castle 1.47 
North  Lima 1.  07 
South  Lima 1.  02 
Indiana 1.  02 
Kansas  oil,  30  gravity .07 
Kansas  oil,  29  gravity .57 
Kansas  oil,  28*  gravity .52 
South  Neodesha .  87 
Corsieana,   light .  85 
Corsieana,  heavy .  50 
Kansas,   heavy •  46 
Bartlesville,  Ind.  T .87 
Somerset 1.01 
Ragland   .60 
Petrolea   (Out) 1.53 
When  Pennsylvania  oil  is  $1.60  the  best  grade  of  Kansas  oil  is  87 
cents,  a  difference  of  73  cents  a   barrel.     This  constant  difference 
