554  Inorganic  Chemistry  of  the  U.S.P.  {^'JZlerXt 
hydrochloric  acid  largely  diluted  with  distilled  water  to  some  potas- 
sium chlorate  contained  in  a  flask.  A  reaction  takes  place,  chlorine 
is  disengaged  and  dissolves  in  the  water.  Chlorine  water  so  made 
is,  of  course,  contaminated  with  certain  subsidiary  matters,  such  as 
free  hydrochloric  acid,  potassium  chloride  and  some  C104,  which, 
however,  do  not  detract  from  its  efficacy  as  a  remedial  agent,  but 
containing  as  it  does  other  substances  besides  chlorine,  dissolved  in 
water,  Aqua  chlori  was  not  considered  a  correct  name,  and  the  title 
Liquor  chlori  compositus  was  adopted.  It  would  seem  perfectly 
proper,  however,  to  retain  the  name  of  Aqua  chlori. 
The  object  of  making  this  change  in  the  preparation  of  chlorine 
water  is  to  avoid  the  very  disagreeable  job  of  preparing  it  as  was 
formerly  done  by  acting  upon  manganese  dioxide  with  hydrochloric 
acid  and  conducting  the  chlorine  gas  into  distilled  water.  The 
operator  during  this  method  exposed  himself  unavoidably  to  the 
pungent  and  very  harmful  chlorine  gas. 
The  product  is  very  unstable,  the  chlorine  uniting  upon  very  short 
exposure  to  light,  with  the  hydrogen  of  the  water,  forming  hydro- 
chloric acid  ;  therefore  it  had  to  be  freshly  made  whenever  wanted. 
The  new  method  enables  the  pharmacist  to  prepare  chlorine  water 
extemporaneously,  rapidly,  and  at  any  time  it  is  called  for,  without 
the  need  of  rigging  up  an  apparatus  and  without  the  exposure  to 
an  irritating  gas.  Chlorine  water  is  official  in  the  German  Pharma- 
copoeia under  the  name  of  Aqua  chlorata.  No  method  of  prepara- 
tion is  given,  but  it  is  directed  to  contain  0-4  to  0-5  per  cent,  of 
chlorine. 
It  is  also  official  in  the  British  Pharmacopoeia  under  the  name  of 
Liquor  chlori. 
The  new  U.S.P.  gives  no  method  for  its  assay  as  did  that  of  1890, 
but  it  directs  that  it  be  freshly  prepared  when  called  for. 
Calx  Chlorata  is  now  more  properly  called  Calx  Chlorinata.  (i  A 
compound  resulting  from  the  action  of  chlorine  upon  calcium 
hydroxide  and  containing  not  less  than  30  per  cent,  of  available 
chlorine.  It  is  often  improperly  called  1  chloride  of  lime.'  It  should 
be  kept  in  well-closed  vessels  and  in  a  cool  and  dry  place."  The 
exact  chemical  constitution  of  this  preparation  is  not  known,  but  it 
is  a  mixture  principally  of  calcium  chloride  and  calcium  hypo- 
chlorite with  some  calcium  hydroxide ;  its  active  constituent  is  the 
hypochlorite,  which  is  a  very  unstable  compound  and  decomposes 
