482 
Studies  on  Licorice  Root. 
S  Am.  Jour.  Pharm. 
(      July,  1921. 
hol,  which  not  only  removes  starch  and  gums,  but  renders  nitration 
easy  on  a  material  which  is  otherwise  very  inconvenient  to  manipu- 
late. Of  all  of  the  acids  proposed  to  precipitate  glycyrrhizic  acid,  he 
finds  sulphuric  to.  he  the  best. 
For  his  control  work  on  the  twenty-seven  methods  for  the  assay 
of  licorice  extract  Linz  has  used  the  Baracco  brand.  It  is  rather 
surprising  that  he  should  have  been  satisfied  to  use  a  material  which, 
as  he  states  himself,  was  characterized  by  an  extraordinary  content 
of  free  copper,  which  he  invariably  found  present,  sometimes  in 
pieces  as  long  as  5  millimeters,  weighing  0.062  grams.  A  product 
so  crudely  made  hardly  seems  the  most  desirable  for  accurate  ana- 
lytical control  work. 
Linz  then  proceeds  to  the  experimental  control  of  the  twenty- 
seven  methods,  and  for  one  reason  or  another  rejects  all  except 
three — those  of  Parry,  Evans'  Sons,  and  Houseman,  and  possibly 
Gadais.  Linz  states  that  the  methods  of  Evans'  Sons  and  myself  are 
both  modeled  on  that  of  Parry. 
I  Avish  at  this  place  to  emphatically  contradict  this  statement. 
On  the  first  page  of  my  article  in  this  Journal,  December,  1912,  I 
clearly  stated  that  Parry  received  his  method  from  me  and  that  the 
MacAndrews  &  Forbes  Company  had  used  it  for  more  than  twenty 
years.  Parry  published  it  without  acknowledgment  of  its  source, 
and  has  contributed  nothing  original  to  the  quantitative  determina- 
tion of  glycyrrhizin.  If  Evans'  Sons  derived  their  method  from 
Parry,  it  is  evident  that  the  method  I  have  given  is  practically  the 
only  original  method  which  Linz  accepts,  from  the  twenty-seven 
proposed.  Subsequent  experience  has  caused  some  modifications  in 
the  method  I  use,  which  I  shall  discuss  later. 
Reply  may  here  be  made  to  minor  criticisms  which  Linz  makes 
of  my  method.  Linz  cannot  understand  why  I  specify  evaporating 
the  alcoholic  solution  of  glycyrrhizin  to  dryness  in  vacuo,  and  as- 
sumes that  I  evaporate  in  vacuo  to  avoid  possible  decomposition  of 
glycyrrhizin,  but  this  is  not  the  case.  There  is  no  danger  of  any 
decomposition  of  glycyrrhizin  during  removal  of  the  acohol.  It  is 
simply  that  I  find  it  a  quick  and  convenient  way  to  completely  re- 
move and  recover  the  alcohol,  the  recovery  being  an  important  mat- 
ter in  these  days.  I  consider  it  undesirable  to  direct  that  the  alcohol 
shall  be  removed  by  "evaporating  to  a  syrup,"  or  "evaporating 
nearly  to  dryness"  on  a  water  bath.  Such  vagueness  easily  permits 
a  trace  of  alcohol  to  remain,  and  that  would  prevent  complete  pre- 
