464       Combination  Percolator  and  Shaking  Tube.  {A™ctobe^9re!m' 
It  is  easy  to  see  that  there  lurks  a  source  of  error  in  the  opera- 
tion of  transferring  the  mixture  of  drug  and  menstruum  from  one 
vessel  to  another,  particularly  in  the  case  of  ethereal  menstrua, 
which  always  have  a  great  tendency  to  "  creep"  to  the  outer  sides 
of  the  vessel. 
In  order  to  avoid  the  necessity  of  transferring  the  mixture  of 
drug  and  menstruum  from  one  vessel  to  another,  I  have  devised  a 
simple  apparatus  by  means  of  which  both  the  shaking  and  the  per- 
colation of  the  drug  with  the  suitable  menstruum  is  carried  out  in 
one  and  the  same  vessel. 
The  apparatus  (see  accompanying  figure)  consists  of  a  cylindrical 
tube  drawn  out  at  both  ends  so  that  it  has  the  shape  of  an  ordinary 
percolator,  but  a  neck  like  an  ordinary  bottle.  The  main  body  of 
the  tube  has  an  inner  diameter  of  25  millimeters  and  is  200  milli- 
meters long.  The  lower,  longer  but  narrower  drawn-out  part  has 
an  inner  diameter  of  14  millimeters  and  is  30  millimeters  long.  At 
the  juncture  of  this  narrow  tube  to  the  main  body  of  the  tube  there 
are  three  rather  deep  indentations  in  the  narrow  tube.1  The  upper 
bottle  neck-shaped  end  of  the  tube  has  an  inner  diameter  of  17 
millimeters  and  is  10  millimeters  long.  The  whole  apparatus  is 
made  of  strong  glass  of  about  I  millimeter  wall  thickness. 
The  tube  is  used  in  the  following  way:  A  piece  of  cotton  is 
placed  in  a  piece  of  cheese-cloth  and  then  pushed  up  from  below 
with  the  cloth  upwards  into  the  narrow  tube  so  that  the  plug 
reaches  the  indentations  and  closes  the  tube  rather  tightly.  The 
plug  is  then  followed  by  more  cotton  so  as  to  nearly  fill  the  narrow 
tube  and  the  latter  is  closed  by  a  good  perforated  cork,  through 
which  passes  a  thin  glass  stop- cock. 
In  the  case  of  ethereal  menstrua  which  percolate  easily,  a  small 
circular  disc  of  filter  paper  can  be  placed  on  the  top  of  the  stop- 
cock.   In  this  case  the  percolate  will  be  perfectly  clear. 
After  closing  the  stop-cock  the  weighed-out  drug  is  introduced 
through  the  open  end  of  the  tube,  and  after  adding  the  proper 
1  Of  the  three  indentations  only  two  are  shown  in  the  figure.  The  indenta- 
tions on  the  outside  are,  of  course,  protuberances  on  the  inside  ot  the  tube. 
