Am.  Jour.  Pharm. 
N  ovember,  1904.  . 
Theory  of  Indicators,  etc. 
513 
free  or  combined  with  proteids.1  In  a  series  of  abnormal  cases,  the 
majority  of  which  were  cancer,  this  was  not  found  to  be  the  case, 
large  differences  amounting  to  as  much  as  6  and  8  c.c.  for  10  c.c. 
of  stomach  contents  being  accounted  for  only  partially  by  the  lactic 
acid  separately  estimated.  In  certain  of  these  cases  one  is  forced 
to  the  conclusion  that  some  secondary  decomposition  of  proteids 
has  led  to  the  liberation  of  carboxylic  groups,  such  as  that  present 
in  aspartic  acid,  for  example,  groups  which,  as  was  shown  in 
Section  IV,  are  capable  of  producing  an  effect  upon  alizarin  or  phe- 
nolphthalein  ;  also  the  weaker  type,  similar  to  that  present  in  as- 
paragin,  glycocol,  leucin  and  tyrosin,  which  are  capable  of  exerting 
an  influence  on  Porrier's  blue.  This  effect  of  liberated  carboxylic 
groups  may  be  recognized  in  another  manner.    If  artificial  peptic 
TABIvE  III. 
Case. 
i 
2 
3 
4 
5 
6 
7 
8 
9 
10 
ii 
12 
Free  and  combined 
HC1  
77 
in 
90 
9'4 
8-o 
5"6 
7'i 
3-6 
2-6 
4'i 
6-6 
6-4 
Total  phosphates    .  . 
Nil 
Nil 
i '5 
•6 
"3 
'4 
•8 
•8 
•4 
'4 
"2 
•6 
77 
in 
IO'O 
8-3 
6-o 
7-9 
4-4 
3'o 
4'5 
6-8 
.  7'o 
Phenolphthalein  end- 
7-6 
io'g 
io"6 
9-6 
8-o 
5"9 
8-3 
4*5 
2-8 
4-6 
6-6 
7'i 
—•i 
—•2 
+-i 
—'4 
—•3 
—•i 
+•4 
+*i 
— "2 
+•1 
—•2 
digests  of  pure  proteids  be  allowed  to  run  for  four,  twenty-four  and 
forty-eight  hours,  respectively,  care  being  taken  to  maintain  exactly 
the  same  conditions  of  working,  and  to  prevent  evaporation  of 
water,  it  will  be  found  that  whilst  the  hydrochloric  acid  and  total 
nitrogen  in  the  mixture  have  remained  perfectly  constant,  as  would 
be  anticipated,  the  phenolphthalein  end  point  has  increased,  the 
alizarin  probably  slightly  diminished,  and  the  drops'  end  point  con- 
siderably diminished,  indicating  an  extension  of  the  range  of  titra- 
tion from  the  phloroglucin  drops'  end  point  to  the  phenolphthalein 
end  point,  due,  presumably,  to  the  liberation  of  basic  groups  on  the 
one  hand,  which  are  capable  of  affecting  the  drops'  end  point  and 
not  the  phenolphthalein  end  point,  and  on  the  other  hand  of  car- 
boxylic groups  capable  of  affecting  the  phenolphthalein  and  not 
1  See  fifth  annual  report  New  York  State  Cancer  Laboratory. 
