per  cubic  foot.  The  difference  in  weight  for  any  particular  Idnd  is  mainly  due  to  a
difference  in  fineness.
494  GAS   PRODUCERS


"tJlster  County  Rosendale  cement  weighs  300  lbs.  per  barrel  net;  Akron,
Milwaukee,  Utica,  and    I^uisville   Rosendales  weigh  265    lbs.    per  barrel    net.     (See

Baker,  "  Masonry-  Construction.")  ,    .,.    r  ,     r  ^  .    «    ,.  7    f

Concrete  Walls.-Concrete  walls  for  houses  are  built  of  1  of  cement  to  6  oi  7  of
broken  stone,  shingle,  gravel,  or  slag.  The  substance  mixed  with  the  cement  must
be  free  from  loam,  fine  sand,  clay,  or  dirt  of  any  kind.  To  prevent  the  cement  from
adhering  to  the  planks  of  the  mold,  apply  freely  to  them  with  a  brush,  soap  boiled  to
the  consistency  of  paint.
WEIGHTS  ^  '-^.
WEIGHT   PER  CUBIC  FOOT  OF   MATERIALS  ^'

Names  of  Substances.  Average  Weight,

Pounds.
