A.m.  Jour.  Pharm. 
Dec,  1884. 
Tests  for  Albumen  in  Urine. 
637 
disordered  health.  If  this  were  not  so,  albuminuria  would  not  be  so 
frequently  unsuspected  and  overlooked  as  it  is. 
Dr.  Roberts  proceeds  to  state  that  "  the  acidulated  brine-test  gave  a 
reaction  in  eleven  cases,  picric  acid  in  fourteen,  the  tungstate  test  in 
twenty-eight,  and  the  mercuric  iodide  in  twenty-nine  cases." 
Deferring  for  the  present  what  I  have  to  say  of  picric  acid,  I  should 
have  expected,  from  observations  which  I  have  quite  recently  made, 
that  the  other  three  tests  would  give  a  slight  but  appreciable  reaction 
in  every  specimen  of  normal  urine.  It  is  a  fact  that  all  normal  urine 
contains  a  small  but  variable  proportion  of  mucus. 
Now,  mucin  is  precipitaed  by  dilute  acetic  acid  and  mineral  acids. 
(See  the  article  "  Mucus,"  in  Watt's  "  Dictionary  of  Chemistry,"  vol. 
iii,  p.  1059-60).  It  is  also  precipitated,  as  Dr.  Oliver  has  shown 
("Bedside  Urinary  Testing,"  p.  37),  by  citric  acid.  The  addition  of 
a  small  quantity  of  acetic  or  citric  acid  to  normal  urine  gradually 
renders  it  slightly  but  decidedly  turbid,  by  coagulating  the  mucin  ; 
and  Dr.  Roberts  mentions  the  fact  that,  when  nitric  acid  is  added  to 
albuminous  urine,  "the  albumen  is  thrown  down  just  about  the  line  of 
junction  of  the  two  liquids,  while  the  mucin  is  brought  into  view 
toward  the  upper  part  of  the  column  of  urine,  where  it  gradually 
forms  a  diffused  haze,  quite  distinct  from  the  opalescent  haze  at  the 
line  of  junction." 
To  this  I  may  add  that,  when  nitric  acid  is  placed  at  the  bottom  of 
a  column  of  normal  urine,  a  diffused  haze  of  coagulated  mucin  may 
commonly,  after  a  time,  be  seen  near  the  upper  part  of  the  column. 
Seeing  then  that  mucin  is  precipitated  by  both  mineral  and  vegeta- 
ble acids,  we  are  at  no  loss  to  understand  that  any  test  containing  one 
or  other  of  these  agents  should  give  a  reaction  with  normal  urine. 
The  acidulated  brine  contains  hydrochloric  acid,  the  tunstate  of  soda 
and  potassio  mercuric  iodide  require  the  addition  of  either  citric  or 
acetic  acid  before  they  act  as  albumen-precipitants  ;  and  they  one  and 
all,  by  the  reaction  with  mucin,  slowly  cause,  in  most,  if  not  all  normal 
urines,  a  cloudiness  more  decided  than  that  which  results  from  the 
action  of  the  acids  alone.  With  picric  acid,  however,  the  case  is 
entirely  different.  In  the  form  of  a  saturated  aqueous  solution,  and 
uncombined  with  any  other  agent,  it  is  a  most  delicate  albumen-pre- 
cipitant, but  it  gives  no  precipitate  in  normal  urine  unless  an  acid, 
such  as  citric  or  acetic  acid,  be  added  to  it.  This  can  readily  be 
proved  by  the  following  experiment.    Take  about  a  drachm  of  freshly 
