162 
Note  on  Minim  Pipettes. 
Am.  Jour.  Pharm. 
April,  1879. 
according  to  the  capacity  of  the  tip.  In  the  30  and  60-minim  gradu- 
ated pipettes  the  tip  is  not  large  enough,  and  hence  the  necessity  of 
resorting  to  the  external  tube  and  its  section  of  rubber  tubing,  as  figured 
by  Mr.  Drew.  For  still  larger  graduated  pipettes,  say  up  to  four 
fluidrachms,  a  common  glass  penis  syringe  with  a  ring  piston  rod  to 
admit  the  end  of  the  forefinger,  and  the  point  armed  permanently  with 
a  short  section  of  rubber  tubing,  wired  securely  onto  the  syringe,  but 
slipping  on  and  off  the  upper  end  of  the  pipette  rather  easily,  answers 
an  excellent  purpose  in  dispensing.  With  such  an  arrangement  small 
quantities  of  liquid  up  to  the  full  capacity  of  the  pipette  can  be  con- 
veniently measured  out  of  a  dispensing  bottle  without  disturbing  the 
sediment  or  wetting  the  neck  or  lip  of  the  bottle. 
If  suction  by  the  mouth  be  used  with  graduated  pipettes  the  mouth 
should  never  be  applied  directly  to  the  pipette,  but  indirectly  by  a  piece 
of  glass  tubing  5  or  6  inches  =12*5  or  1 5  centimeters  long,  armed 
with  a  piece  of  rubber  tubing  wired  onto  it  2  to  3  inches  =5  to  7*5 
centimeters  long.  The  free  end  of  this  rubber  tubing  is  slipped  on 
and  off  of  the  pipette  when  used.  The  pipette,  with  the  auxiliary  tube 
attached,  is  introduced  into  the  liquid  to  be  measured  and  held  with 
the  left  hand,  the  free  end  of  the  auxiliary  glass  tube  is  held  by  the 
teeth,  and  the  graduations  being  brought  up  to  near  the  level  of  the 
eyes  by  the  bending  of  the  rubber  part  of  the  tube,  suction  is  made 
gently  till  the  liquid  rises  in  the  pipette  a  little  above  the  required  mark 
on  the  graduated  scale.  Then  the  rubber  tube  is  pinched  by  the  thumb 
and  finger  of  the  right  hand  close  above  the  end  of  the  pipette  ;  the 
glass  tube  is  dropped  from  the  mouth,  and  the  level  of  the  liquid  is 
adjusted  to  the  desired  graduation  by  allowing  the  excess  drawn  in,  to 
escape  back  into  the  bottle.  When  the  exact  quantity  is  contained, 
the  whole  is  transferred  by  the  right  hand  to  the  bottle  or  vessel  which 
is  to  receive  the  measured  quantity,  and  the  pinching  of  the  rubber 
part  of  the  tube  being  then  relaxed,  the  liquid  flows  out. 
Brooklyn,  March  nth,  1879. 
