460 
ANTISEPTIC  PROPERTIES  OF  AMMONIA. 
to  place  in  the  jar  with  the  specimen  a  layer  of  felt  or  lint, 
charged  with  from  ten  minims  to  a  drachm  of  the  liquor  am- 
monia fortis,  and  then  to  close  the  vessel  or  jar  secure  from  the 
external  air.  For  a  luting  in  such  cases  soap  answered  best,  or 
a  mixture  of  soap  and  red  lead.  After  this  description,  Dr. 
Richardson  pointed  out  the  practical  value  of  the  method.  1st. 
In  conducting  post-mortem  inquiries  it  did  away  with  all  occasion 
for  hurry.  It  was  now  only  necessary  at  an  autopsy  to  be  pro- 
vided with  one  or  more  jars,  each  containing  say  a  drachm  of 
liquid  ammonia.  The  jars  might  now  be  filled  with  specimens, 
and  if  the  stoppers  were  put  in  with  care  the  specimens  would 
retain  their  freshness  for  weeks,  and  even  their  microscopical 
characters.  The  only  peculiar  change  was,  that  if  much  fat 
were  present,  the  alkali  formed  with  it  a  kind  of  soap ;  a  fact 
which  explained  the  formation  of  adipocire  in  the  dead  subject 
undergoing  slow  decomposition.  For  forensic  purposes  this 
method  of  preserving  animal  structure  was  perfect,  inasmuch  as 
it  added  no  mineral  or  poisonous  matter,  and  yet  secured,  the 
part  to  be  examined  free  from  change  and  from  all  offensive 
odor.  Not  only  so,  but  important  pathological  changes,  such 
as  ulceration  of  intestine,  could  be  kept  under  observation  and 
submitted  to  any  number  of  pathologists.  He  (Dr.  Richardson) 
had  found  the  system  a  very  useful  one,  too,  for  lecture  pur- 
poses, as  it  enabled  him  to  show  to  his  class  real  specimens  of 
disease,  such,  for  instance,  as  the  scirrhous  breast  now  going 
round,  instead  of  casts  or  specimens  softened,  discolored,  and 
indeed  destroyed  altogether  by  immersion  in  spirit.  The  last 
point  to  which  Dr.  Richardson  drew  attention  had  reference  to 
the  cause  of  the  antiseptic  power  of  ammonia.  Ammonia  being 
a  product  of  decomposition  had  been  looked  on  commonly  as  a 
substance  provoking  decomposition.  But  ammonia  was  truly 
the  most  powerful  antiseptic  known  :  it  acted  catalytically  by 
preventing  the  union  of  oxygen  with  oxidizable  bodies.  An  ex- 
periment was  here  performed  illustrating  this  :  half  a  grain  of 
ammonia  diffused  through  40  cubic  inches  of  air  was  shown  to 
possess  the  power  of  entirely  suspending  the  combination  of 
oxygen  with  potassium  on  a  surface  of  paper  saturated  with 
iodide  of  potassium,  starch,  and  solution  of  oxygen,  so  long  as 
the  paper  was  presented  to  the  ammoniated  air ;  but  so  soon  as 
