146 
DISINFECTION  OF  NITROGENOUS  MANURE. 
our  knowledge  we  may  briefly  enumerate  the  chief  emanations 
from  night-soil,  with  the  best  disinfectant  or  corrective  known,  as 
follows  : 
1.  Sulphydric  acid ;  sulphate  of  zinc  or  of  iron,  (vitriol  solu- 
tion.) 2.  Carbonate  of  ammonia ;  sulphate  of  lime,  (powdered 
plaster.)  3.  Free  carbonic  acid  ;  lime,  (quick  or  slaked.)  4. 
Putrid  exhalations,  (not  investigated ;)  charcoal,  (better  fresh 
and  powdered.)  Only  a  very  small  portion  of  vitriol  solution  is 
necessary  at  one  time,  and  this  should  be  so  sprinkled  over  the  mass 
as  to  meet  the  gases  rising  to  the  surface.  Plaster,  lime,  and 
charcoal  may  be  used  more  freely  ;  yet  a  small  portion  of  these, 
if  frequently  strewed  upon  the  surface,  will  be  sufficient.  It  has 
been  suggested  that  the  disinfectant  be  supplied,  as  water  is, 
from  a  reservoir,  by  simply  turning  a  faucet. 
In  the  manufacture  of  poudrette  the  chief  objects  are,  first, 
to  preserve  all  the  fertilizing  matter  of  night-soil ;  and  secondly, 
to  expel  the  excess  of  water,  amounting  in  some  instances  to 
nine-tenths  of  the  whole  volume,  (ordinary  excrements  when  fresh 
are  four-fifths  water.)  An  excellent  method  of  accomplishing 
these  objects  is  to  mix  thoroughly  with  the  night-soil  a  solution 
of  sulphate  of  zinc,  and  leave  at  rest  for  a  time,  when  the  wa- 
tery portion  may  be  pumped  off  and  allowed  to  flow  into  a  sew- 
er or  gutter,  (Paris  Medical  Police,)  without  forming  a  nuisance. 
It  may  be  well  to  allow  a  small  jet  of  solution  of  sulphate  of 
zinc  to  mix  with  the  stream  (Messrs.  Quesney)  as  it  issues  from 
the  pump.  The  disinfected  residue  in  the  vault  may  now  be  re- 
moved, spread  in  thin  layers  on  a  resin  or  other  water-tight  floor, 
(A.  Wallet,)  and  allowed  to  evaporate  to  dryness  under  an  open 
shed  or  by  furnace  heat.  The  poudrette  has  been  sometimes 
pressed  in  cubical  masses,  pierced  with  holes,  to  promote  desicca- 
tion. Thus  prepared  it  requires  no  packing  for  transportation 
or  preservation.  A  little  rain  will  do  it  no  harm  if  the  wet  sur- 
face be  immediately  dusted  with  plaster.  Poulet  has  recom- 
mended the  employment  of  an  emulsion  of  oils  and  alkalies  in 
connection  with  the  zinc  salts,  in  order  to  obtain  a  clearer  li- 
quid to  pump  off. 
But  the  better  method  is  recommended  by  Susser  &  Fouchet, 
Lepelletier,  (Moniteur  Industriel,)  by  which  all  the  mineral  and 
organic  matters  are  entrapped  in  a  gelatinous  precipitate  of  silica. 
