1.  a.  100  gr.  of  the  sample  for  examina-
tion (fairly  selected)  are  crushed  to  a  powder,
and  placed  on  a  small,  weighed,  and  perfectly
dry  paper  filter,  and  then  desiccated,  by  expo-
sure for  2  or  3  hours  to  the  heat  of  boiling
water.  The  loss  in  weight,  taken  in  grains,
after  dedacting  9,  indicates  the  quantity  per
■  '  Eleni.  of  Agric  Chem.'


cent,  of  water  or  moisture  which  the  sample
contains  in  excess  of  that  present  in  good  or
pure  guano.i

h.  The  paper  filter,  with  its  contents,  is  next
suspended  for  some  time  over  concentrated  sul-
phuric acid  (oil  of  vitriol)  contained  in  a  wide-
mouthed  bottle  or  jar,  by  means  of  a  thread
attached  to  the  cork  or  stopper,  care  being
taken  to  exclude  the  external  air.  The  expo-
bure  in  this  way  is  continued  until  the  gnano
ceases  to  diminish  in  weight,  which  is  ascer-
tained by  weighing  it  at  intervals  after  the
first  3  or  4  hours.  When  this  point  is  arrived
at,  the  filter  and  its  contents  are  very  carefully
weighed.  The  difference  between  its  present
weight  and  its  original  weight  (before  the
desiccation  in  a),  taken  in  grains,  gives  the
gross  quantity  of  water  per  cent,

<.-.  The  dried  guano  from  b  is  next  placed
in  a  weighed,  smooth  crucible  or  capsule,  and
exposed  to  a  low  red  heat  until  all  the  or-
ganic matter  is  completely  destroyed,  and  the
whole  is  reduced  to  a  white  ash,  which  is
weighed  as  soon  as  it  has  become  cold.
