330  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,  1906,  PART    I. 
is  equipped  with  6  blunger  mills,  7  oscillating  screens,  104  bolting! 
cloth  screens,  17  settling  tanks  (some  of  30,000  gallons  capacity),  10 
filter  presses,  and  15  ovens  of  12  cars  capacity  each.  The  value  of 
the  clay  is  reported  to  be  $5.50  a  ton.  A  royalty  of  25  cents  a  ton 
of  refined  clay  is  paid  to  the  owner  of  the  land. 
York  Clay  Company. — The  mine  of  the  York  Clay  Company  adjoins 
the  Philadelphia  mine  to  the  west.  The  mill  wTas  examined,  but  not 
the  mine,  as  the  manager,  John  Allen,  was  absent  at  the  time  of  the 
writer's  visit.  The  practice  here  has  been  to  mine  by  .large  shaft  to 
the  maximum  depth  profitable,  which  is  about  90  feet,  and  then 
abandon  this  for  a  new  shaft.  At  the  time  of  the  writer's  visit  the 
company  was  operating  in  a  round  shaft  21  feet  across  and  50  feet  in 
depth,  with  steam  bucket  hoist.  The  clay  is  hauled  by  wagon  700 
feet  to  the  mill.  The  company  also  has  a  tunnel  150  feet  into  the 
mountain  to  the  clay  and  a  drift  along  the  bed  250  feet.  Sloping 
had  been  carried  20  feet  above  the  tunnel.  A  small  amount  of  iron 
ore  was  passed  through  before4  reaching  the  clay.  The  beds  seem  to 
lie  (latter  here  than  at  the  Philadelphia  mine,  although  it  may  be 
that  the  drifts  have  not  yet  been  carried  back  far  enough  to  strike 
the  original  bedded  deposit. 
The  product  is  refined  in  the  company's  mill  on  the  property.  It 
firsl  passes  through  two  washers  lit  ted  with'  vertical  paddles  and  then 
one  with  horizontal  paddles,  from  which  it  flows  as  a  thin  slip  through 
about  400  feet  of  very  gently  inclined  flotation  troughs  built  side  by 
side  in  50-fool  lengths.  The  sand  is  deposited  in  these  troughs  and 
is  removed  by  shovel,  the  clay  remaining  in  suspension.  The  slip  is 
further  filtered  through  revolving  wire  screens  and  collected  in  set- 
tling tanks,  of  which  there  are  five.  After  about  two  days  the  clear 
water  is  drawn  oil'  and  the  thick  slip  is  forced  through  presses,  3  in 
number,  similar  to  those  of  the  Philadelphia  (day  Company.  The 
corrugated  cakes  are  transferred  by  cars  directly  to  the  drying  tunnel, 
which  is  heated  by  steam  pipes  to  190°.  The  dried  (day  that  is  not 
sold  in  bulk  is  pulverized  in  an  old  thrashing  machine,  with  a  cup 
chain  attachment  which  delivers  the  powder  into  a  vertical  bin  for 
bagging.  The  capacity  of  the  mill  was  reported  to  be  between  1!)  and 
13  tons  a  day. 
The  Mount  llolhi  Brick  and  (:/<n/  Company-  Through  the  courtesy 
of  the  manager,  Charles  Blissard,  much  information  regarding  the 
plant  and  mines  of  this  company  was  obtained,  and  the  property 
was  carefully  inspected.  The  brick  plant  and  clay  refinery  are  located 
in  the  town  of  Mount  Holly  Springs,  where  they  were  constructed 
with  the  expectation  that  the  clay  mined  in  the  vicinity  of  the  town 
would  furnish  an  amply  supply  for  operating  the  refinery  and  that 
the  siliceous  waste  and  impure  clay  could  be  used  in  the  brick  plant. 
The  supply  of  white  clay,  however,  w^as  soon  exhausted,  and  in  1898 
