Am'JJu0ly^9oh3arm•}     Quantitative  Estimation  of  Phosphates.  325 
throw  more  light  on  the  constitution  of  this  interesting  nitrogenous 
derivative. 
It  has  been  shown  that  the  alkaloidal  modification  of  our  sub- 
stance can  take  up  four  acid  radicals.  This  is  proved  by  the  fact 
that  monobenzoyl  epinephrin,  C17H]7N04,  is  capable  of  taking  up 
three  acetyl  groups.  Inasmuch  as  this  monobenzoyl  compound  was 
formed  by  benzoylating  the  native  principle  as  existing  in  extracts 
of  the  gland,  it  may  be  assumed  that  epinephrin  hydrate  also  is 
capable  of  taking  up  at  least  four  acid  radicals.  This  point  is  now 
being  put  to  the  test  by  experiment.  The  above  experiments, 
nevertheless,  show  that  we  already  have  some  little  insight  into  the 
chemical  character  of  this  interesting  compound. 
A  NOTE  ON  THE  QUANTITATIVE  ESTIMATION  OF 
PHOSPHATES  IN  STOMACH  CONTENTS. 
By  G.  H.  A.  Clowes,  Ph.D., 
Gratwick  Research  Laboratory,  University'  of  Buffalo. 
Having  had  occasion  in  the  course  of  the  last  two  or  three  years 
to  make  a  large  number  of  analyses  on  normal  and  pathological 
stomach  contents,  I  have  had  the  opportunity  of  remarking  how 
absolutely  unreliable  are  the  various  volumetric  estimations,  and 
further,  that  the  ideas  generally  held  regarding  the  significance  of 
individual  titrations  are  frequently  erroneous.  It  has  been  found 
necessary  in  our  work  on  metabolism  to  make  gravimetric  deter- 
minations of  the  various  constituents  wherever  the  stomach  con- 
tents were  concerned.  I  do  not  propose  in  this  paper  to  deal  with 
the  various  phases  of  this  subject,  which  will  be  reserved  until  the 
completion  of  some  work  now  in  progress  on  cancer  of  the  stomach  ; 
but  simply  with  the  estimation  of  acid  phosphates,  which  affords  a 
good  illustration  of  the  errors  of  volumetric  analysis. 
Phosphoric  acid  is  tri-basic;  that  is  to  say,  is  possessed  of  three 
hydrogen  atoms  capable  of  being  displaced  by  monovalent  bases,  as 
sodium,  potassium,  etc.  Each  of  these  hydrogen  atoms  can  be  sat- 
urated separately  and  the  end  point  of  each  may  be  very  readily 
determined  as  follows : 
A  solution  of  phosphoric  acid  is  prepared  and  titrated  by  means 
