242 
Chemistry  of  Digestion. 
f  Am.  Jour.  Pharm. 
t        May.  1892. 
indicator).  The  figure  found,  expressed  in  hydrochloric  acid,  repre- 
sents the  total  chlorine  T  contained  in  the  original  liquid. 
b  is  left  on  the  water  bath  for  an  hour,  then  an  excess  of  carbonate 
of  sodium  is  added,  and  it  is  evaporated  afresh  and  tested  for 
chlorine,  as  above. 
The  figure  given  by  b  represents  all  the  chlorine  less  the  free 
hydrochloric  acid,  a  —  b  =  HC1  free.  After  drying  c  it  is  carefully 
calcined,  avoiding  all  super-elevation  of  temperature.  After  cooling, 
the  chlorine  is  tested,  as  above,  and  the  figure  for  fixed  chlorine  is 
is  obtained;  b  —  c  equals  the  chlorine  combined  with  organic  mat- 
ters and  ammonia. 
(1)  T  (the  total  chlorine)  undergoes  very  regular  variations  at 
different  hours  of  digestion.  At  the  first  period  it  increases,  the 
increase,  however,  not  being  proportioned  to  the  time  ;  the  duration 
of  the  period  depends  upon  the  kind  of  animal,  on  the  individual 
and  the  nature  of  the  food.  Whatever  the  kind  of  food,  the  phe- 
nomenon is  more  rapid  the  lighter  the  meal  is.  During  the  first 
hour  it  is  the  greatest.  The  maximum  of  chlorine  is  found  in  the 
second  hour  when  a  light  meal  is  taken  (a  quarter  of  a  litre  of  tea 
and  60  grammes  of  bread),  but  it  is  retarded  when  lighter  food  is 
taken.    Afterwards  the  chlorine  decreases  more  or  less  rapidly. 
(2)  Chlorine  fixed  (F).  This  may  arise  from  the  food  or  the 
secretions.  In  the  former  case  a  maximum  figure  is  found  at  the 
beginning;  in  the  second  case  it  will  increase  unless  it  is  trans- 
formed by  digestion  ;  there  would  then  be  other  chlorine  combina- 
tions. The  second  is  actually  what  occurs.  When  water  is  introduced 
into  the  stomach  of  fasting  dogs  its  digestion  is  accompanied  by  a 
rapid  increase  not  only  of  the  total  chlorine  but  of  the  fixed  chlorine. 
When  both  solids  and  liquids  are  given,  digestion  may  be  divided 
into  two  periods.  In  the  first,  the  total  chlorine  increases  more 
rapidly,  and  the  fixed  CI  tends  towards  a  certain  limit,  about  which 
it  oscillates.  Later,  the  total  chlorine  arrives  at  its  maximum,  and 
diminishes,  whilst  the  fixed  chlorine  rises,  and  undergoes  conse- 
quently an  inverse  variation  to  that  of  the  total  chlorine.  At 
the  beginning  of  digestion  the  total  chlorine  preponderates 
very  much  over  the  fixed,  and  the  difference  is  so  much  the  greater 
as  the  food  is  more  solid.  This  difference  depends  besides  on  indi- 
vidual conditions. 
(3)  Free  HC1,  designated  by  the  letter  H,  often  fails  in  the  gastric 
