'^'jin!?,'  mT^'' }     Liquid  and  Saccharated  Pepsins.  3' 
sists  of  a  cylindrical  iron  vessel  R,  about  16  inches  in  diameter.  The  lower  end 
of  the  exchanger  coil  P,  is  connected  with  the  lower  end  of  another  coil  in  a 
similar  vessel  beside  it,  called  the  complement,  S,  (fig-.  1)  the  upper  end  ofwhich 
complement  coil  T,  enters  the  absorption  vase  M  (fig.  2),  at  the  top,  and  de- 
scends nearly  to  the  bottom. 
"At  first  the  boiler,  exchanger,  complement,  and  absorption  vase,  are  charged 
with  aqua  ammonias,  but  as  soon  as  the  heat  from  the  boiler  coil  U,  (fig.  1)  has 
driven  off  sufficient  gas  to  create  strong  pressure,  the  weakened  hot  aqua 
amraoniae  is  forced  from  the  boiler  A,  into  the  coil  of  the  exchanger  P,  where 
it  is  partially  cooled  by  the  cold  aqua  ammonias  of  the  absorption  vase  M,  which 
the  pump  Y,  (fig.  2)  has  forced  into  the  cylinder  of  the  exchanger  P,  ready  to 
replace  the  weak  aqua  ammonise  in  the  boiler  A.  The  weak  aqua  ammonise  is 
then  perfectly  cooled  as  it  passes  through  the  complement  coil  T,  which  is  sur- 
rounded by  cold  water,  and  it  (the  weak  aqua  ammoniae)  enters  the  absorption 
vase  M,  rapidly  absorbing  the  gas  entering  from  the  collector  L,  thus  repro- 
ducing aqua  ammoniae.  Simultaneously,  the  forcing  pump  Y  of  the  machine 
is  drawing  the  cool  strong  aqua  ammoniae  from  the  under  stratum  in  the  ab- 
sorption vase  M,  and  forcing  it  in  the  cylinder  of  the  exchanger  R,  where,  after 
performing  its  office  of  cooling  the  weak  aqua  ammoniae  and  becoming  itself 
heated,  it  passes  into  the  boiler  A,  near  its  top,  impinging  on  a  series  of  porous 
diaphragms  of  metal  W,  (fig.  1)  suspended  in  the  upper  part  of  the  boiler  A, 
to  facilitate  the  rapid  separation  of  the  gas  a  second  time.  Thus  it  is  apparent 
that  the  same  aqua  ammoniae  may  be  used  over  and  over  again. 
"  At  starting  the  machine,  all  the  cans  J  are  filled  with  pure  water,  and  closely 
covered  with  wooden  lids,  and  when,  after  four  hours,  they  are  completely 
frozen,  the  operator  removes  the  ice,  which  is  effected  by  simply  dipping  the 
cans  momentarily  in  hot  water,  and  then  inverting  them.  The  cakes  of  ice  are 
uniformly  rectangular,  and  as  their  temperature  when  removed  is  far  below  32^ 
Fahr.,  by  simply  moistening  their  surface  they  freeze  perfectly  to  each  other, 
and  form  solid  blocks  of  ice  of  any  required  dimensions." 
The  reader  is  referred  to  our  article  at  page  102,  March,  1870,, 
from  which  the  above  is  extracted,  for  some  further  remarks. 
LIQUID  PEPSIN  AND  SACCHARATED  PEPSIN. 
By  E.  Schefffk. 
In  my  essay  upon  Liquid  Pepsin  [Am.  Jour.  Pharm.^  March,  1870j 
doubts  were  expressed  about  the  durability  of  the  preparation  during 
warm  weather.  Subsequently,  as  the  weather  became  warmer,  I  found 
that  a  mould  was  forming  in  the  liquid,  the  quicker,  the  less  perfectly 
the  mucus  was  separated  from  it,  and  also  when  the  bottle  containing 
it  was  from  time  to  time  opened,  so  that  the  air  could  come  in  contact 
with  it. 
To  satisfy  myself  I  filtered  a  fresh  prepared  liquid  repeatedly,  un- 
