The  condensation  apparatus  1  and  8  is  com-
posed of  rows  of  Woulfe's  bottles,  partly  filled
with  water,  care  being. taken  to  place  the  first
pairs  of  these  bottles  in  a  tank  of  cold  water.
The  condensation  of  tlie  last   portions  of

>  In  South  Lancasliire  alone,  more  tlian  1000  tons  ot
lljilnicbloric  acid  in  solution  are  made  ncekly.
^^a'^^''^v>'t^^


hydrochloric  acid  gas  is  effected  either  by  the
aid  of  the  coke  columns,  or  in  leaden  oham-
beis,  into  which  fine  jets  of  cold  water  are  in-
jected on  all  sides.
"A  saturated  solution  of  hydrochloric  acid  in
water  has  the  specific  gravity  of  1-21;  and  when
heated  in  a  retort,  loses  at  first  hydrochloric
ai;id  gas,  but  after  a  time  an  aqueous  acid
distils  over,  at  the  ordinary  atmospheric  pres-
sure, containing  2022  per  cent,  of  hydro-
chloric acid,  and  boiling  constantly  at  110°  C.
If  the  distillation  be  conducted  under  dimin-
ished pressure,  the  liquid  boils  at  a  lower
temperature,  and  attains  a  composition
which  is  different  for  each  boiling  point;
hence  the  dilute  acids  thus  obtained  by
boiling  the  solution  of  hydrochloric  acid  gas
in  water,  cannot  be  considered  as  definite  com-
pounds of  hydrochloric  acid  and  water."'
>  Roscoe  and  Dittmar.
852


HYDROCHLORIC  ETHER— HYDROCYANIC  ACID


Fib.  3.
Fir  3


Commercial  hydroelilorio  acid  is  usually  of
a  yellow  colour  otviiig  to  its  being  contami-
nated with  iron.  It  also  very  frequently  con-
tains sodium,  arsenic,  sulphuric  and  sulphurous
acids,  and  free  chlorine.
