4I2 
Methods  of  Estimating  Tannins. 
{Am.  Jour.  Pharm. 
Aug.,  1877. 
have  mnch  the  appearance  of  a  peeled  orange,  or  of  the  capsule  of 
Papaver  hybridum,  L.  This  variety  is  not,  however,  readily  accepted 
in  commerce. 
The  seeds  of  the  white  poppy  are  sown  in  rows  about  20  inches 
apart.  When  young  the  plants  require  constant  weeding.  The  capsule, 
when  the  flower  has  fallen,  is  about  the  size  of  a  walnut,  and  is  stated 
by  Mr,  Usher  to  grow  to  the  size  of  an  orange  in  the  short  space  of 
ten  days,  although  it  takes  nearly  five  weeks  to  ripen.  Each  plant  bears 
about  two  or  three  capsules.  The  harvest  is  collected  during  the  last 
week  in  August  or  the  first  in  September.  A  wagon  load  of  the  cap- 
sules is  placed  on  the  floor  of  each  of  the  kilns  and  forms  a  layer  about 
a  yard  deep,  the  whole  of  which  becomes  dry  in  about  twelve  hours, 
and  is  then  ready  for  sale. — Phar.  Jour,  and  Trans.,  June  16. 
SOME  METHODS  OF  ESTIMATING  TANNINS.1 
By  H.  R.  Proctor,  F.C.S. 
There  are  few  substances  of  equal  importance  to  the  tannins,  of 
which  the  chemistry  is  in  so  unsettled  a  state.  This  is,  no  doubt, 
primarily  due  to  their  complexity  and  unstable  character,  which  makes 
their  investigation  one  of  great  difficulty  ;  and,  secondarily,  to  the 
indifference  and  ignorance  of  chemistry  of  those  to  whom  the  know- 
ledge is  of  commercial  importance.  But  tanners  may  be  well  excused 
for  some  distrust  of  chemical  analyses  when  we  consider  the  discordant 
results  which  are  yielded  by  most  of  the  processes  in  use.  With  a 
view  to  exhibit  the  relative  merits  of  these  processes,  I  have  ventured 
to  give  the  results  of  comparative  experiments  undertaken  to  test  their 
accuracy,  and  to  point  out,  if  possible,  those  which  merit  confidence. 
The  process  which  has  been  brought  most  prominently  before  the 
public  of  late  is  that  of  Muntz  and  Ramspacher,  which  consists  in 
forcing  a  tannin  infusion  through  a  piece  of  raw  hide,  taking  the  sp.  gr. 
before  and  after,  and  calculating  the  tannin  from  the  loss.  In  a  paper 
which  I  communicated  to  this  Society  some  little  time  since  (Proceed- 
ings, III,  213),  I  pointed  out  that  the  raw  hide  not  only  absorbed  the 
tannin,  but  also  a  large  proportion  of  the  free  acids  in  the  infusion, 
thus,  in  some  cases,  causing  a  notable  error.    To  this  I  may  now  add 
1  From  the  Transactions  of  the  Newcastle-upon-Tyne  Chemical  Society,  1874- 
1877. 
