GLASS-MAKING  MATERIALS. 
During  the  last  season  several  importanl  glass-manufacturing  districts  have  been  visitei 
by  Survey  geologists,  and  careful  investigation  has  been  made  of  the  glass  sands  and  oilier 
raw  materials  used  in  the  manufacture  of  this  product.  The  results  of  this  work  arc  sural 
notarized  in  the  following  three  reports: 
THE  REQUIREMENTS  OF  SAND  AND  LIMESTONE  FOR  GLASS 
MAKING. 
By  Ern est  !•'.  Bi  i:<  hard. 
INTRODUCTORY    STATEMENT. 
The  data  for  the  following  paper  were  derived  from  a  brief  >tnd\  of  the  glass  sands  of 
the  middle  Mississippi  basin.  (ila^>  manufacture  admits  of  such  slight  variations  in  the 
character  of  its  raw  materials  that  the  materials  used  from  the  Cent  ral  States  are  regarded 
as  representing  very  fairly  the  grade  demanded  for  the  industry  a!  large.  The  points 
considered  in  this  paper  are  intended  mainly  to  serve  as  a  guide  to  persons  who  wish  to 
know  whether  certain  sandstones  or  limestones  may  he  suitable  for  glass  making.  There- 
fore only  the  chemical  and  physical  p  operties  are  taken  up  here,  and  the  consideration 
of  other  conditions  on  which  the  value  of  a  deposit  depends  is  reserved  for  the  paper  "Glass 
sands  of  the  middle  Mississippi  basin,"  pages  159    17'J  of  this  bulletin. 
LITERATURE. 
The  statistic^  of  the  product  ion  of  glass  sand  in  L902,  L903,  and  1904  have  been  gathered 
and  com | tiled  by  A.  T.  Coon-  and  published  each  year  by  tin'  Survey  in  "  Mineral  Resources 
of  the  United  States.'"  These  reports  have  been  freely  used  in  preparing  papers  for'  this 
bulletin.  Besides  these  reports  there  i-  no!  much  literature  dealing  directly  with  glass 
sand,  hut  nearly  all  technical  papers  or  manuals  on  the  subject  of  glass  contain  useful  data 
with  regard  to  the  sand.      Among  such  technical  paper-  may  be  mentioned  the  following: 
Weeks,  J.  !>.,  Glass  materials:  Mineral  Resources  U.  S.  for  L883  84,  (J    S.  Geol.  Survey,  1885. 
Biser,  I'..  !•"..  Elements  of  Glass  and  Glass  Making,  L899. 
Linton,  Robert  Glass  Making  in  the  United  States:   Eng.and  Min.Jour.,  vol.  68,  No.  10, 1899,  p.  454. 
Linton,  RoBERT.Glass:  Mineral  [ndustry  for  L899,  L900,  pp  234  263. 
Gillinder,  James,  Gla      Manufactures  in  America :  Encyclopedia  Americana,  vol.  8. 
Austin.  Siiiri.ky  I'..  Class.  Twelfth  Census  <»f  the  United  States  vol.  9,  Manufactures,  pt .  3,  1902, 
pp.  941-KMM). 
Uhlig,  E.  ('..  chemical  Analysis  for  Glass  Makers,  1903. 
Grimsley,  G.  I'..  Manufacture  of  glass  in  Kansas:  Firsl  biennial  reporl  Kansas  Bureau  of  Labor. 
1901-2,  1903,  pp.  343-346. 
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