10  0.0365

14    0.05

20    0.073

27    O.I

34  0.125

40  0.146

48  0.175

50  0.182

55  0.2

61  0.225

70  0.25

73  0.275

80  0.292

87  0.317

90  0.329

95  0.347

100  0.365

105  0.383

109  0.4

Free  Hydrochloric  Acid,  Mintz  Method. — Ten  cc.  of  the  filtered
gastric  juice  are  titrated  with  tenth-normal  NaOH  until  the  test  for
free  acid  is  no  longer  positive.  This  is  based  on  the  supposition  that
the  NaOH  will  neutralize  the  free  before  the  bound  HCl.
Of  indicators  there  are  several.  Undoubtedly  the  most  accurate
is  the  Giinzberg.  As  the  sodium  hydroxide  is  added,  small  drops  of
the  stirred  fluid  are  removed  by  a  glass  rod,  or,  better  still,  a  platinum
oesa,  and  tested  on  a  porcelain  dish  (see  page  314).  Fleiner  adds  25
to  30  drops  of  the  Giinzberg  reagent  directly  to  the  gastric  juice,  and
then,  as  the  sodium  hydroxide  is  added,  removes  small  drops  which  he
warms  in  a  porcelain  spoon.  Sahli  recommends  that  the  glass  rods
themselves  with  which  the  soda  is  stirred  into  the  gastric  juice  be
warmed,  since  the  crimson  color  can  be  seen  on  the  rod.  He  also
adds  from  25  to  30  drops  directly  to  the  fluid.  In  this  method  a  certain
amount  of  gastric  juice  is  lost  in  each  of  the  tests,  and  hence  the
results  should  be  confirmed  by  a  new  portion  from  which  less  is  re-
moved.
