458 
CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,  1905. 
REQUIREMENTS   OF   LIMESTONE. 
In  its  connection  with  sand  as  n  glass  material  limestone  is  of  interest  to  quarrymeri  i 
As  shown  in  the  table  on  page  453,  limestone  enters  the  hatch  of  several  kinds  of  glass  to  tin 
extent  of  about  IS  per  cent  of  its  mass.  The  rock  is  crushed,  ground  finely,  and  screened 
Purity  is  ;is  essential  in  lime-tone  as  in  sand,  and  it  is  probable  that  much  of  the  impurity 
which  finds  its  way  into  the  hatch  comes  unsuspectedly  from  the  limestone.  Limestone 
therefore,  should  be  analyzed  frequently,  as  it  may  carry  clay  and  iron  pyrites  as  well  as 
carbonates  of  iron  and  magnesia,  all  of  which  are  objectionable  for  reasons  previously  staled. 
Moreover,  beds  in  the  same  quarry  often  vary  in  composition  within  short  distances,  lame- 
stone  of  good  quality  belonging  mainly  to  the  Carboniferous  system  is  widely  distributed 
in  Illinois.  Missouri,  Kansas,  and  other  central  glass-manufacturing  State-,  and,  compared 
with  sand,  it  brings  a  high  price.  Analyses  of  certain  lime-tones  used  in  this  industry  are 
given  below,  and  many  suitable  limestones  are  described  by  Mr.  E.  ('.  Eckel  in  Bulletin 
No.  243,  on  the  Cemenl  Materials  and  Industry  of  the  United  States. 
Analyses  oflimestont  used  in  glass  making. 
Locality. 
Lime  car- 
bona  te 
(Ca<  Oj 
Magne 
siuiii  car 
bonate 
o 
Iron  oxide 
,  K,..(, ... 
Alumina 
1  UjOa). 
Silicates 
and  silica 
(SiOs). 
i.  Meramec  Qua rrj  I  "..  w  ick<  s,  Mo 
2.  Meramec  Qua  rry  Co.,  Wickes,  M<> 
97.96 
97.  7'-' 
97.23 
o.o 
.  is 
0.0 
1     is 
0.59 
8.  S7 
1  .  Sli 
.20 
(FesCOs.) 
.  L6 
I.  in 
.02 
l.oi 
1.  Pennsylvania 
1.01 
i.  I''.  P.  Mason,  analysl . 
2.  Win.  Chauvenel .  anal}  st. 
3.  S.  E.  Swartz,  analysl . 
■i.  Mia.  [ndustrj  tor  L899,  p.  240. 
