638 
Tests  for  Albumen  in  Urine. 
Am.  Jour.  Pharm. 
Dec,  1884. 
passed  normal  urine,  and  add  an  equal  bulk  of  picric  acid  solution. 
The  yellow  mixture  will  remain  quite  clear,  unless,  as  sometimes 
though  rarely  happens,  some  turbidity  results  from  a  deposit  of  urates, 
which  would  be  at  once  removed  by  heat.  Now  add  a  few  drops  of 
dilute  acetic  or  citric  acid,  and  the  mixture  will,  in  a  minute  or  two, 
become  hazy  from  precipitated  mucin,  the  haziness  occurring  much 
more  slowly  than  the  immediate  opalescence,  which  results  from  the 
presence  of  a  slight  trace  of  albumen,  but,  like  that,  being  unchanged 
by  heat. 
Another  experiment  consists  in  adding  acetic  or  citric  acid  to 
normal  urine,  then,  after  waiting  a  minute  or  two  to  complete  the 
coagulation  of  the  mucin,  passing  the  urine  through  a  filter  and  adding 
picric  acid  to  the  filtrate ;  when  the  mixture  will  remain  quite  free 
from  turbidity.  I  have  tested  many  hundred  specimens  of  normal 
urine  with  picric  acid,  and  I  confidently  assert  that  in  such  specimens, 
no  precipitate  or  haziness  occurs  when  unmixed  picric  acid  is  used  as 
the  test-agent;  and  it  may  be  that  the  different  results  with  this  test 
obtained  by  Dr.  Roberts  are  due  to  his  having  added  acetic  or  citric 
acid  to  the  picric  acid  in  his  experiments.  The  only  precipitates  other 
than  albuminous  which  may  result  from  picric  acid,  employed  alone, 
are  urates  which  rarely  occur,  except  when  the  mixture  is  allowed  to 
stand  for  some  time ;  peptones,  which  I  have  met  with  only  twice  in 
as  many  years ;  and  vegetable  alkaloids,  such  as  quinine,  when  large 
doses  are  being  taken.  These  all  differ  from  an  albuminous  precipitate 
in  the  fact  that  they  are  readily  and  completely  redissolved  by  heat, 
while  they  may  be  distinguished  from  each  other  by  the  microscope. 
(See  the  author's  lectures  on  "Albumen  and  Sugar  Testing,"  p.  11, 
Smith,  Elder  &  Co.) 
It  appears,  therefore,  from  very  numerous  and  careful  observations, 
that  albumen  is  the  only  substance  found  in  the  urine  which  gives  with 
picric  acid  a  precipitate  insoluble  by  heat. 
The  difference,  then,  between  picric  acid  and  the  other  new  tests  for 
albumen  is  this — that  picric  acid,  unmixed  with  other  reagents,  while 
it  is  a  most  sensitive  and  trustworthy  test  for  albumen,  gives  no  reaction 
with  mucin.  On  the  other  hand,  the  potassio-mercuric  iodide,  tungs- 
gate  of  soda,  and  brine,  do  not  precipitate  albumen,  unless  when 
combined  with  an  acid  ;  and  this  combination  gives  a  reaction  with 
mucin,  which  is  not  distinguishable  from  a  minute  trace  of  albumen. 
I  have  been  in  the  habit  of  using  the  potassio-mercuric  iodine  only 
