446  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,  1906,   PART    I. 
USES. 
, 
The  uses  to  which  infusorial  earth  can  be  put  are  constantly  bein 
found  to  be  more  numerous,  and  the  methods  for  its  application  are 
developing.     Formerly  it  was  employed  solely  for  abrasive  purposes,! 
and  this  use  has  been  extended  in  the  manufacture  of  polishing  pow- 
ders,  scouring  soaps,   etc.     But  its  principal  uses  are  now  others. 
It  is  of  value  in  the  manufacture  of  dynamite  from  nitroglycerine, 
owing  to   its  porosity,   which   makes  it  a  good   absorbent.      Being  a 
poor  conductor  of  heat  and  very  light,  it  is  valuable  for  use  in  the 
manufacture   of   packing   for  safes,   steam    pipes,   and   boilers  and   of 
fireproof  building  materials  such  as  hollow  bricks  for  partition  walls, 
floors,  etc.,  solid  bricks,  furnace  bricks,  and  tiles;  also  as  a  base  inl 
the  manufacture  of  cements  suitable  for  withstanding  fire  and  heat. 
On   account    of   its   porous  yet    compact    character   it   makes  a   good 
filtering  substance,  and  is  so  used  commercially.     This  use  is  facili-1 
tated    when    the   tripoli   can   be   obtained    in   compact  blocks  of  the  J 
required   size.     The  California   product    is  very  easily  cut  into  any! 
shape  desired.     Tripoli   powder  is  also  used   in   the   manufacture  of 
plaster.     Some  of  the  earth   from   the   Lompoc  region,  it   is  said,  is 
sent  to  a  large  neighboring  refinery   for  use  in   the  refining  of  beet 
sugar.      An  interesting  use  to  which   the  raw    material   is  put   in  the] 
Lompoc  region  and  also  at   Monterey,  farther  north  on  the  California  I 
coast,  is  in  the  construction  of  buildings.     The  shale  is  easily  quar- 
ried  into  smooth  blocks,  which,  owing  to  their  light  weight,  can  bel 
readily   placed    in    position.      A    number  of  buildings  have  been   very 
successfully  constructed  in  this  way.     The  shale  blocks  are  compact 
and  vet  elastic  under  changes  of  temperature,  seem  to  possess  suffi- 
cient strength,  and  owing  to  the  siliceous  composition  of  the  material 
arc  very  resistant   to  weathering.     Such  building  material  would  be  j 
finely  adapted  to  regions  subject  to  earthquakes,  owing  to  the  prob- 
able lesser  effects  of  shocks  on  so  light  a  substance  and  the   smaller 
amount  of  damage  that  would  result  from  falling  materials. 
PRODUCTION    IN   THE   UNITED    STATES. 
Infusorial  deposits  occur  in  many  States.  Those  producing  it  for 
economic  use  in  1903  were,  in  the  order  of  importance,  together  with 
the  number  of  concerns  engaged  in  its  exploitation,  Missouri  (3  pro- 
ducers), Virginia  (2),  New  York  (2),  California  (3),  Maryland  (1), 
Georgia  (1),  Massachusetts  (1),  New  Hampshire  (1),  Florida.  (1).  In  j 
1004  the  order  changed  somew  hat .  as  follows:  Missouri  (2  producers),  j 
Maryland  (1),  California  (2),  Virginia  (1),  Florida  (1),  New  Hamp- 
shire (1),  New  York  (1).  Massachusetts  (1),  and  Georgia  (1).  The 
amount  and  quality  of  the  material  in  California  warrants  the  proph- 
ecy that  it  will  lead  in  the  production  before  long  and  supply  enough 
to  make  it  unnecessary  to  import  any  such  products  from  abroad. 
