224 Pharmacopceial  Assays  of  Drugs  and  Galenicals. {AmMay?i89oarm' 
cient  to  establish  the  identity  and  purity  of  the  drug  and  the  product 
obtained.  Incidentally  it  may  be  remarked,  that  the  German 
Pharmacopoeia,  which  requires  a  minimum  of  only  io  per  cent,  of 
resin,  will  probably  reduce  the  amount  to  8  per  cent.,  and  the  same 
may  be  necessary  in  this  country,  although  it  is  well  known  that 
roots  of  much  higher  grade  may  be  found.  As  it  is  likely  that  the 
subterraneous  part  of  the  plant  will  survive  the  winters  in  most 
sections  of  the  Southern  and  Central  United  States,  it  is  to  be 
hoped  that  its  cultivation,  which  appears  to  present  no  difficulties 
or  unusual  labor,  may  be  undertaken,  so  that  a  supply  of  better 
quality  of  the  drug  may  be  regularly  obtainable.  In  regard  to  the 
ether-soluble  portion  of  the  drug,  it  is  well  known  that  its  percentage 
varies;  but  in  the  past  experience  of  the  writer,  it  rarely  exceeds  io 
per  cent,  of  the  total  resin,  and  is  mostly  less  than  this  amount. 
Since  the  water-soluble  portion  of  the  alcoholic  extract  of  jalap  pos- 
sesses decidedly  purgative  properties,  it  may,  however,  be  questioned 
whether  an  assay  of  the  drug,  based  solely  upon  its  resinous  con- 
stituents can  secure  the  absolute  uniformity  of  other  galenical 
preparations  than  the  officinal  resin,  and  it  is  obvious  that  for  pre- 
paring the  latter,  a  previous  assay  is  not  necessary. 
In  suggesting  the  standardization  of  other  pharmacopceial  drugs, 
writers  have  usually  selected  such  wThich  contain  alkaloids,  and  for 
determining  the  percentage  of  the  latter,  recommended,  in  most 
cases,  either  the  volumetric  estimation  of  the  liberated  alkaloids  by 
acids,  or  the  employment  of  Mayer's  solution.  Though  this  test 
liquid  is  an  excellent  reagent  for  alkaloids,  it  cannot  lay  claim  for 
giving  unvarying  results,  since  these  are  in  many  cases  affected  to  a 
considerable  extent  by  different  degrees  of  dilution.  And  since  its 
general  behavior  to  all  alkaloids  is  alike,  the  precipitates  obtained 
with  it  from  acidulated  solutions  merely  prove  the  (probable)  pres- 
ence of  alkaloid  without  identifying  it.  Such  a  process  evidently 
lacks  the  first  requisite  of  a  legal  requirement,  definiteness;  for 
pharmacopceial  purposes  it  would  be  applicable  only  to  the  drug  as 
there  described,  but  not  to  the  powder,  tincture,  extract  or  other 
galenical  preparations. 
But  is  there  really  such  an  urgent  necessity,  overpowering  every 
other  consideration,  for  requiring  all  drugs  furnished  by  nature  to 
contain  a  definite  percentage  or  a  minimum  amount  of  a  certain 
constituent,  or  mixture  of  constituents  ?    This  is  extremely  doubt- 
