Am.  Jour.  Pbarm.\ 
February,  1904.  j 
Lime  Water, 
69 
The  first  of  these  is  to  use  a  lime  that  has  been  thoroughly  cal- 
cined, and  then  to  wash  the  resulting  hydrate  with  distilled  water, 
or  at  least,  boiled  and  cooled  water,  until  all  traces  of  soluble  salts 
have  been  eliminated. 
The  use  of  distilled  or  boiled  water  is  to  be  recommended,  as  it 
facilitates  the  production  of  a  more  uniform,  as  well  as  a  more  stable 
preparation.  This  is  to  a  large  extent  due  to  the  fact  that  the  con- 
tained gases,  particularly  the  carbon  dioxide,  have  been  eliminated. 
In  this  same  connection  it  may  be  well  to  call  attention  to  the  fact, 
noted  by  several  of  the  investigators  quoted  above,  that  slaked  lime 
that  contains  more  than  from  25  to  30  per  cent,  of  carbonate  is  not 
suited  for  making  lime  water,  as  this  contained  carbonate  appears  to 
interfere  with  or  to  impede  the  solution  of  the  hydrate. 
A  slight  change  in  the  Pharmacopceial  directions  for  making  lime 
water  would  also  appear  desirable.  If  instead  of  directing  approxi- 
mately 1  part  of  lime  to  300  of  water,  the  Pharmacopoeia  directed  1 
part  of  lime  to  25  or  30  parts  of  the  solvent  and  allow  the  water  to 
be  replaced  from  time  to  time,  or  as  long  as  the  magma  contains  a 
sufficient  quantity  of  hydrate  to  readily  yield  a  satisfactory  product, 
the  directions  would  correspond  more  closely  with  the  practice  as 
usually  followed. 
The  German  Pharmacopoeia  directs  that  lime  water  should  be 
filtered  and  dispensed  perfectly  clear  and  free  from  any  suspended 
carbonate.  This  provision  might  well  be  included  in  our  own  Phar- 
macopoeia, providing  that  the  first  portions  of  the  filtrate  be  directed 
to  be  thrown  away.  This  would  be  indicated  by  the  fact  that  filter 
paper  has  a  peculiar  affinity  for  calcium  hydrate,  so  much  so  that 
the  first  portions  of  lime  water  passing  through  a  filter,  lose  from 
15  to  20  per  cent,  of  the  contained  alkali. 
One  other  precaution  that  might  well  be  observed  in  the  making 
of  lime  water  is  to  use  cold  water,  and  to  keep  the  lime  water  con- 
tainers in  a  cool  place  where  they  will  not  be  subjected  to  sudden 
or  extreme  changes  of  temperature. 
The  more  desirable  Pharmacopceial  changes  might  be  summed 
up  as  follows : 
Increase  the  relative  amount  of  lime  and  permit  the  use  of  succes- 
sive quantities  of  water. 
Direct  that  lime  water  be  dispensed  clear,  and  that  when  filtered 
the  first  portion  of  the  filtrate  be  thrown  away. 
