464 
Theory  of  Indicators,  etc. 
/  Am.  Jour.  Pharm. 
I     October,  1904. 
ing  between  various  weak  basic  groups  all  in  the  presence  of  one 
another  without  interference  with  one  another  by  means  of  the  four 
indicators  enumerated  above. 
V.  BEHAVIOR  OF  INDICATORS  TOWARDS  PROTEIDS,  ALBUMOSES, 
PEPTONES,  ETC. 
In  order  to  test  the  effect  on  indicators  of  proteids  and  various 
products  obtained  from  the  latter  by  partial  or  complete  hydrolysis, 
we  made  use  of  albumin  solutions  and  solutions  ot  Witte's  peptone, 
especially  prepared,  artificial  peptic  digestion  of  egg-white,  tryptic 
digestion  of  egg-white,  etc. 
(1)  The  behavior  of  egg  albumin  was  tested  by  separating  the 
white  of  two  eggs  and  thoroughly  admixing.  Portions  of  10  c.c. 
were  then  removed  and  titrated  with  phenolphthalein,  alizarin  and 
phloroglucinvanillin,  and  I  c.c.  quantities  were  made  use  of  for  the 
estimation  of  nitrogen.  This  same  experiment  was  repeated  with 
two  more  eggs,  the  only  difference  being  that  in  the  second  case  the 
egg-white  was  first  thoroughly  admixed  with  ten  times  its  volume 
of  water  before  making  titrations  and  determining  nitrogen.  Results 
are  as  follows : 
EXPERIMENT  I. 
10  c.c  =  i'i  c.c.  acid  to  phenolphthalein. 
"      ............      =  7  6  c.c.  acid  to  alizarin. 
"   =  20  *6  acid  to  drops. 
1  c.c.  N  =  12*6  n/10  acid, 
from  which  it  will  be  noticed  that  the  portion  from  phenolphthalein 
to  alizarin  is  about  one-half  of  that  from  alizarin  to  drops,  and  that 
the  whole  range  from  phenolphthalein  to  drops  is  about  one-sixth  of 
the  total  N. 
EXPERIMENT  2. 
100  c.c.  of  the  diluted  solution  .  .  .  .  =  i*6  c.c.  acid  to  phenolphthalein. 
"    «    <<    "       «  «        .  .  .  .  =  8 'o  c.c.  acid  to  alizarin. 
"    "    "    "       "          "        ....  =22  0  c.c.  acid  to  drops. 
Nitrogen  1  c.c   =13 'o  c.c.  n/ioacid, 
from  which  it  will  be  noticed  that  the  phenolphthalein  to  alizarin 
bears  about  the  same  proportion  to  that  from  alizarin  to  drops,  I  to 
2,  as  in  the  previous  case,  and  also  that  the  total  effect  on  indicators 
in  titration  is  about  one-sixth  of  the  total  nitrogen  equivalent,  as 
previously  observed. 
