598  Valuation  of  Drugs  and  Foods.  {X™*ZS£X^ 
well  known.  We  have  already,  in  a  previous  portion  of  this  paper, 
referred  to  the  value  of  the  microscope  for  this  purpose.  We  may 
add,  however,  that  not  only  are  the  spectroscope  and  polariscope 
valuable  adjuncts  in  the  examination  of  drugs,  foods  and  prepara- 
tions, but  the  micro-polariscope  and  micro-spectroscope  each  reveal 
certain  characteristics  which  are  deserving  of  greater  attention 
than  they  have  heretofore  received.  A  mere  mention  is  made  of 
these  facts  at  this  time,  and  will  be  dwelt  upon  more  fully  in  a  sub- 
sequent paper. 
CONCLUSION. 
From  this  rather  broad  consideration  of  this  subject,  the  value  of 
which  can  only  be  confirmed  in  some  instances  by  the  experiments 
of  future  investigations  and  by  the  experiments  of  a  number  of 
workers,  it  is  apparent  that  the  valuation  of  the  various  medicinal 
substances  is  dependent  upon  a  large  number  of  very  different 
methods,  involving  a  knowledge  of  many  branches  of  science. 
The  author  is  well  aware  that  some  of  the  methods  proposed  will 
have  to  be  worked  over  very  carefully  before  they  can  be  adopted  with 
any  degree  of  authority.  But  it  was  considered  desirable  to  bring 
this  subject  to  a  focus  in  this  manner  so  that  an  opportunity  might 
be  afforded  all  of  us  to  work  along  lines  which,  while  involving  the 
highest  technical  skill  and  training  on  the  one  hand,  would,  on  the 
other  hand,  bring  to  light  methods  for  the  valuation  of  drugs  which 
would  be  inexpensive  and  practicable  to  the  retail  pharmacist.  It 
seems  to  the  author  that  each  drug  has  properties  or  constituents 
which  will  make  it  possible  for  it  to  be  valued  in  one  of  the  four 
general  classes  of  methods  proposed,  viz.:  (i)  Chemical;  (2)  physi- 
cal ;  (3)  biological ;  (4)  optical. 
Each  of  these  methods  will  be  shown  to  have  its  limitations,  and 
in  some  cases  several  or  all  methods  may  be  advantageously  em- 
ployed. 
While  there  are,  no  doubt,  imperfections  in  this  paper,  still  if, 
on  the  basis  of  the  experiments  already  carried  out  by  the  author 
and  other  investigators,  and  as  suggested  in  this  paper,  methods 
may  be  at  least  devised  which  will  have  a  practical  value  to  the 
retail  druggist  in  either  elaborating  upon  or  approximately  esti- 
mating the  value  of  his  purchases  of  vegetable  drugs,  the  work 
upon  the  paper  will  not  have  been  in  vain. 
