^eceinhe^'iS!1*}       Valuation  of  Drugs  and  Foods.  593 
(d)  Gentian  Root. — 0-500  gramme  of  the  finely  powdered  drug 
is  shaken  with  500  c.c.  of  H20  for  a  few  hours.  Ten  c.c.  of  the 
filtered  solution  are  diluted  with  10  c.c.  of  water.  A  few  cubic 
centimeters  of  this  solution  give  the  characteristic  taste  of 
gentian. 
(e)  Calumba. — The  solutions  of  this  drug  correspond  essentially 
to  gentian,  imparting,  however,  the  characteristic  taste  of  calumba- 
(2)  A  very  appreciable  difference  in  the  quality  of  some  drugs 
containing  volatile  oils  is  manifest  on  treating  O-IOO  gramme  of 
the  dm*  with  1  c.c.  of  deodorized  alcohol  and  noting  the  odor 
produced  by  a  small  quantity  dropped  on  a  piece  of  filter  paper. 
In  this  manner  the  superiority  of  Penang  to  Zanzibar  cloves  is  at 
once  discerned.  The  differences  in  the  odor  of  solutions  of  the  cin- 
namons is  probably  even  more  marked. 
On  mixing  0"iooo  gramme  of  black  mustard  in  a  porcelain  cap- 
sule with  sufficient  water  to  moisten  it,  there  is  immediately  de- 
veloped a  pronounced  and  persistent  odor  of  the  volatile  oil  of 
mustard. 
(3)  The  sense  of  touch  is  employed  by  millers  to  some  extent, 
but  probably  has  more  value  as  a  qualitative  test.  Brokers  who 
deal  in  cereals,  however,  use  the  sense  of  touch  in  the  "dough- 
ing  test,"  which  is  employed  in  determining  the  value  of  commer- 
cial flours. 
(4)  In  regard  to  the  employment  of  color  as  a  test,  it  may  be  said 
that  certain  drugs  and  foods  develop  characteristic  colors  when 
moistened  with  water  or  alcohol  or  upon  treatment  with  chemi- 
cals, as,  for  example,  in  the  latter  instance,  the  action  of  iodine  and 
phloroglucin.  The  intensity  of  the  colors  produced  is,  in  a  meas- 
ure, of  quantitative  as  well  as  qualitative  value. 
(7/  E)  We  now  come  to  consider  what  promises  to  be  one  of 
the  most  important  problems  involved  in  the  valuation  of  drugs, 
viz.,  that  of  pharmacological  assay.  For  our  purposes  the  work  may 
be  divided  into  a  number  of  classes  depending  upon  the  class  of  or- 
ganisms that  are  affected.  The  following  subdivisions  may  be  made  : 
(1)  effects  upon  micro-organisms;  (2)  effects  upon  insects;  (3)  ef- 
fects upon  lower  animals,  as  eggs  of  sea-urchins,  fish,  guinea-pigs, 
rabbits,  dogs,  etc. ;  (4)  effects  upon  man. 
(1)  The  study  of  the  action  of  drugs  upon  micro-organisms,  and 
the  study  of  the  products  produced  by  these  organisms,  belongs 
