Am.  Jour.  Pharm, 
November,  1899. 
}      Valuation  of  Drugs  and  Foods. 
533 
Kino  requires  that  300  c.c.  of  water  be  added  to  the  5  c.c.  of 
solution  of  the  drug  to  produce  a  corresponding  intensity  of  color. 
Galls,  on  the  other  hand,  require  that  to  5  c.c.  of  the  original  solu- 
tion as  many  as  400  c.c.  of  water  be  added  to  obtain,  with  ammonio- 
ferric  alum,  a  coloration  that  is  equal  in  intensity  to  that  of  the 
solutions  of  the  other  drugs  mentioned. 
There  is  a  slight  difference  in  the  color  of  the  solutions  obtained 
and  a  more  marked  difference  in  the  color  of  the  precipitates.  Pre- 
cipitates of  oak  bark,  with  ammonio-ferric  alum,  have  a  slightly 
greenish-brown  color ;  those  of  geranium  and  galls  have  a  light 
pinkish-blue  color;  those  of  catechu  and  kino  are  more  or  less 
grayish-blue  or  violet ;  and  that  of  krameria  has  a  slightly  deeper 
gray  color. 
We  find  that  the  amount  of  water  necessary  to  be  added  to  5  c.c. 
of  the  solution  of  the  drug  in  order  to  produce  solutions  of  equal 
intensity  increases  with  the  amount  of  tannin  in  the  drug,  as  the 
following  figures  indicate  : 
Drug. 
Per  Cent,  of  Tannin. 
(Approximately.) 
Number  of  C.c  of  Water 
be  Added  to  5  C.c.  of  Solu- 
tion of  Drug  (each  C.c.  of 
which  has  '005  Gramme  0 
Drug). 
Quercus  alba  
6-1 1  per  cent. 
25  C.C. 
20  " 
l6o  " 
12-27  " 
1 80  " 
35       "  • 
200  " 
50 
300  " 
50-60 
400  " 
(E)  Working  on  a  similar  basis,  it  is  possible  to  get  relatively 
approximate  values  with  those  drugs  that  contain  oxymethylan- 
thraquinone  or  some  of  its  derivatives.  In  this  case  -ioo  gramme 
of  the  drug  is  boiled  for  a  few  minutes  with  a  solution  containing 
N  • 
5  c.c.  KOH  _  -f  1 5  c.c.  water.  The  amount  of  water  that  is  required 
to  be  added  to  produce  a  light  straw  color  is  noted.  In  the  follow- 
ing table  is  given  a  list  of  substances,  the  number  of  cubic  centi- 
metres of  water  required  to  be  added  to  them  to  produce  colors 
of  nearly  equal  intensity,  and  the  dose  of  the  drug  in  grammes : 
