AmkJa°rcii  tt8ym" }  New  Process  for  Estimating  Tannin  Volumetrically.  121 
influence,  if  any,  organic  substances  might  have  upon  the  results. 
The  following  table  gives  the  figures  obtained: 
Substance. 
Amount. 
Sol.  of  hypo- 
chlorite used 
Tannin 
found. 
Tannin 
calculated. 
Difference. 
010  Gm. 
0-15  " 
0-20  " 
0'30  " 
14  c  c. 
10-5  cc. 
13-9  cc. 
20-8  cc. 
c  
0-075  Gm. 
0-099  " 
0148  " 
0-075  Gm. 
o-ioo  " 
0-150  " 
0-000  Gm. 
o-ooi  " 
0-002  " 
This  series  of  analyses  demonstrates  that  with  this  test  a  most  ex- 
cellent approximation  may  be  made  to  the  quantity  of  tannin  present, 
and  that  sugar  has  no  influence  on  the  results.  With  this  process, 
an  assay  of  commercial  tannin  can  be  made  in  less  than  ten  minutes. 
In  further  extension  of  this  subject,  it  may  be  said  by  the  trans- 
lator of  the  above  that  some  time  ago,  without  any  knowledge  of  the 
existence  of  this  method,  he  endeavored  to  discover  a  practical 
method  of  tannin  analysis  based,  as  in  this  process,  on  the  decompo- 
sition of  ink,  using,  however,  a  neutral  solution.  For  that  purpose 
I  employed  ammonia  water,  which,  whilst  it  changed  the  ink  to  a 
reddish  color  in  very  dilute  solution,  with  the  precipitation  of  ferric 
oxide,  was  inapplicable  for  general  practice,  because  of  a  somewhat 
similar  action  upon  other  organic  matter.  Potassium  hydrate  had  a 
like  influence.  The  ferric  tannate  is  also  decolorized  by  chlorine 
water,  diluted  sulphuric,  nitric,  hydrochloric,  nitrohydrochloric,  or 
phosphoric  acids.  Strong  acetic  acid  exerts  no  change  upon  it. 
Gallic  acid  in  a  dilute  inky-rendered  solution,  is  altered  in  color  by 
AraHO'or  KHO,  with  the  formation  of  a  deep  rosy-colored  solu- 
tion, resuming  its  original  tint  on  neutralization  with  acetic  acid. 
Ferric  gallate  is  destroyed  in  color  by  chlorine  water,  diluted  sul- 
phuric, nitric,  hydrochloric,  nitrohydrochloric  or  phosphoric  acids,  but 
not  by  strong  acetic  acid.  Hypochlorites  will  also  destroy  its  color, 
but  alkaline  chlorides  make  no  change. 
It  may  be  suggested  that  sodium  hypochlorite,  in  the  form  of 
"  Labarraques'  Solution,"  deprived  of  free  chlorine  gas,  be  employed 
instead  of  the  calcium  compound,  as  more  readily  applicable,  since 
the  results  afforded  by  each  are  the  same.  The  contained  sodium 
chloride  exerts  no  action  upon  the  tannin-ink,  so  the  change  is 
