220  Pharmacopceial  Revision  and  Assays.  {AmMay!"iSoarm' 
skill  and  ability  would  have  a  maximum  range  of  probable  error  of 
not  more  than  a  half  of  one  per  cent,  above  or  below  the  truth — 
might  be  better  adapted  to  the  pharmacopceial  usage  of  the  present 
time,  than  a  critically  accurate  chemical  process  with  a  range  of 
error  of  a  tenth  of  a  per  cent. — first  because  no  two  samples  of  the 
same  lot  of  Opium,  whether  moist  or  in  powder,  would  come  within 
this  small  range  of  error  ;  and  next,  because  such  a  process  would 
require  a  degree  of  expert  knowledge  and  skill  rarely  found  in 
pharmaceutical  practice. 
Another  important  consideration  not  to  be  overlooked  is,  that 
with  the  exceptions  of  Cinchona,  Jalap,  Opium  and  Scammony,  the 
drugs  named  can  always  be  bought  by  pharmacopceial  descrip- 
tion and  tests,  of  such  quality  as  to  yield  preparations  of  practically 
uniform  therapeutic  value.  The  claim  frequently  heard  that  all 
pharmaceutical  preparations  from  crude  drugs  should  be  made  or 
adjusted  by  assay  is  so  plausible  and  attractive,  as  to  form  a  most 
fertile  basis  for  specious  advertising  by  manufacturers  of  these  pre- 
parations, and  if  the  Pharmacopoeia  could  be  committed  to  this  or 
any  similar  doctrine  it  would  put  much  money  into  the  pockets  of 
large  manufacturers,  and  just  to  that  extent  would  divert  practical 
pharmacy  from  its  legitimate  channels  and  proper  responsibilities. 
In  the  first  place,  the  claim  is  untrue  and  unfair  because  a  very  large 
proportion  of  important  drugs  have  no  separable  active  principle 
that  can  be  determined  by  assay,  and  therefore  their  quality  cannot 
be  determined  by  assay,  nor  can  their  preparations  be  adjusted  by 
assay.  Out  of  some  ninety  officinal  drugs  in  all,  there  are  about 
thirty-four  of  the  more  important  ones  which  may  be  fairly 
represented  by  Ergot,  Rhubarb,  Senna,  Wild  Cherry,  Dandelion, 
Columbo,  Gentian,  Butternut,  Pareira,  Cotton  Root,  Cimicifuga, 
Buckthorn,  Leptandra,  Sarsaparilla,  Spigelia  and  Stillingia,  which 
could  not  be  adjusted  by  any  ordinary  processes  of  assay,  and  which 
do  not  need  it  if  they  could,  because  care  in  buying  them  by  phar- 
macopceial description  and  tests,  rather  than  by  price,  will  always 
easily  obtain  a  uniform  good  quality,  at  moderate  cost.  Again, 
while  a  fair  degree  of  accuracy  and  uniformity  in  the  strength  of 
galenical  medicines  is  most  desirable,  any  strain  after  a  degree  of 
accuracy  that  is  not  necessary,  nor  available  if  attained,  is  hurtful 
by  whatever  is  sacrificed  to  attain  it.  In  the  therapeutic  uses  of 
medicines,  doses  are  anything  but  definite  or  accurate  in  quantity. 
