172  Study  of  Urine,  Sputum  and  Blood.  {AmAJp°r,ur;Srm' 
few  drops  of  Sterling's  stain1  to  the  specimen  and  steam  over 
a  flame  for  from  one  to  two  minutes ;  remove  this  stain  by 
washing  in  water  and  then  add  a  few  drops  of  a  30  per  cent,  solution 
of  nitric  acid.  Continue  the  acid  until  the  specimen  has  apparently 
given  up  all  its  blue  color  ;  wash  in  water  and  add  saturated  alcoholic 
solution  of  Bismarck  brown  for  one-half  minute.  Again  wash  and 
dry  between  layers  of  filter  paper.  The  specimen  can  now  be 
mounted  in  Canada  balsam,  and  when  studied  under  the  1-12  (oil 
immersion)  lens  the  tubercle  bacillus  is  stained  violet,  while  all 
other  organisms  and  cellular  elements  are  stained  brown.  My 
reasons  for  using  this  stain  are  :  (1)  You  are  never  dependent  upon 
an  uncertain  quantity,  Gabbett's  acid  blue  solution.  (2)  Bacteria, 
commonly  met  with  in  sputum,  are  better  stained  by  Bismarck 
brown  than  by  acid  blue.  (3)  It  is  easier  for  the  untrained  eye  to 
detect  a  violet  bacillus  on  a  brown  surface  than  to  detect  the  same 
organism  stained  red  when  surrounded  by  an  indefinite  blue.  The 
study  of  pus  is  not  dissimilar  to  that  of  sputum  ;  however,  it  is  well 
to  stain  several  specimens,  one  of  which  should  be  with  the  view  of 
detecting  the  tubercle  bacillus  and  one  by  Gram's  method. 
The  preparation  of  cover-glasses  and  slides  is  all-important  in  the 
study  of  blood.  Cover-glasses  on  coming  from  the  factory  are  usu- 
ally covered  with  a  fine  film  of  dust,  which  is  best  removed  by 
washing  them  with  soap  and  water,  taking  each  glass  between  the 
thumb  and  finger  and  rubbing  with  a  soft  handkerchief  until  it  is 
clean,  when  it  can  be  dried  with  another  handkerchief  and  dropped 
into  a  perfectly  clean,  wide-mouthed  bottle,  which  is  carefully 
corked.  Treating  these  glasses  with  strong  mineral  acids  often 
fixes  the  dust  to  the  glass  and  makes  it  troublesome,  if  not  im- 
possible to  remove.  I  see  no  advantage  in  keeping  clean  covers 
or  slides  in  a  mixture  of  alcohol  and  ether. 
In  preparing  to  examine  the  blood  of  a  patient,  it  is  well  to 
place  a  piece  of  filter  paper  in  the  bottom  of  a  Petri  dish  and  to 
remove  from  the  bottle  as  many  covers  and  slides,  by  means  of 
JR    Gentian  violet,  10  grammes 
Anilin  oil,  4  " 
Alcohol  (95  per  cent.),     20  " 
Aqua  Dest,  176  c.c. 
Add  the  anilin  oil  to  the  alcohol  and  dissolve  gentian  violet  in  water.  Add 
solution  of  gentian  violet  gradually,  shaking  between  each  addition  ;  filter. 
