520 
Theory  of  Indicators,  etc. 
Urn.  Jour.  Pharm 
I  November,  1904. 
with  different  varieties  of  serum,  all  of  them  being  slightly  acid  to 
phenolphthalein,  requiring  from  i  to  -2  c.c.  of  n/io  solution;  and 
alkaline  to  alizarin,  requiring  from  -4  to  -6  c.c. ;  strongly  alkaline  to 
phloroglucinvanillin  drops,  the  end  point  varying  from  1-2  to  1-6. 
The  total  nitrogen  of  the  serum  appears  to  be  about  five  times  the 
total  range  from  phenolphthalein  to  the  drops'  end  point.  The  end 
point  of  Porrier's  blue  lies  slightly  below  that  of  phenolphthalein^ 
and  the  precipitation  point  of  proteids  appears  to  coincide  fairly 
well  with  the  end  point  of  alizarin  or  to  lie  slightly  beyond.  The 
effect  of  phosphates  is  not  large  enough  to  account  for  the  titration 
differences,  giving  an  average  of  -2  from  the  phenolphthalein  to  the 
alizarin  end  point  and  -2  from  the  alizarin  to  the  drops'  end  point. 
It  is  therefore  apparent  that  the  proteids  themselves  play  an  impor- 
tant role  in  affecting  the  end  point  of  given  indicators.    The  varia- 
table  v. 
Indicator  or 
Reagent. 
Guinea  Pig. 
Rabbit. 
Bullock. 
Hog. 
Antitoxic 
Horse  Serum. 
Phenolphthalein 
+  'i 
-r  "i 
+  '1  to  '2 
+  "05  to  -i 
+  'i 
Alizarin  .... 
—  *5 
—  •6 
—  '4  to  -5 
-•65 
—  '7 
—  1*2 
—  1  "45 
—  1-4  to  1  "5 
—  1  "55 
—  r6  to  17 
tions  from  the  normal  observed  in  human  beings  under  pathological 
conditions  will  be  dealt  with  in  another  publication. 
The  wide  variation  between  the  end  points  of  the  three  indicators 
employed  above  on  titrating  blood  serum,  emphasizes  the  necessity 
of  establishing  certain  uniform  standards  when  determining  the 
degree  of  alkalinity  of  blood  serum  in  pathological  cases.  To  avoid 
confusion  when  titrating  blood  serum  from  cases  of  diabetic  coma 
or  cancer  cachexia,  it  has  been  customary  in  this  laboratory  to 
determine  the  end  point  of  the  indicators  enumerated  above,  as  well 
as  that  of  lakmoid,  which  seems  to  have  been  fairly  extensively 
employed  for  this  purpose. 
X.  TITRATION  OF  URINE. 
The  discussion  of  this  subject,  so    far   as  pathological  con- 
ditions are  concerned,  will  be  reserved  for  another  publication 
but  it  may  be  remarked  that  under  normal  conditions  the  urine 
•is  about  equally  acid  to  phenolphthalein  and  alkaline  to  alizarin,. 
