Am.  Jour.  Pharm. ) 
July,  1883.  / 
Facts  Concerning  Filtration. 
353 
near  the  bottom  of  the  cylinder  being  fitted  with  a  short  female 
screw  of  the  same  pitch  of  thread.  Over  the  tray  the  filtering  mate- 
rial (d)  (flannel,  calico,  paper  supported  by  muslin,  or  any  other 
that  may  be  suited  to  the  liquid 
to  be  operated  on)  is  tied  securely  ; 
it  is  then  inverted  and  placed  in 
the  cylinder  so  that  the  holes  b 
and  are  exactly  opposite  one 
another.  A  tap  (e)  with  a  bend 
at  a  right  angle  is  screwed  in  so 
that  it  holds  the  two  together  and 
assists  a  short  leg  (f)  in  support- 
ing the  tray  in  position.  To  the 
end  of  the  tap  is  attached  an  india- 
rubber  tube  turned  on  itself  (g), 
or  a  long  glass  tube  of  similar 
construction  (in  fact  like  a  large 
safety  funnel  deprived  of  the  thistle 
head),  which  can  be  attached  by  a 
short  piece  of  rubber  tube.  It 
will  be  obvious  that  any  com- 
munication between  the  tap  and 
the^  contents  of  the  vessel  must 
be  made  through  the  filtering  me- 
dium which  covers  the  inverted 
tray,  and  that  any  deposition 
which  takes  place  must  be  on  the 
bottom  of  the  vessel  itself  or  on 
the  opposite  side  of  the  tray,  but 
not  on  the  filtering  surface,  and 
herein  lies  the  special  advantages  of  the  filter  I  now  introduce.  The 
use  of  a  long  delivery  tube  is  not  new ;  it  formed  part  of  an  oil  filter 
patented  by  Mr.  Britten,  of  Liverpool,  some  years  before  Mr.  Schacht's 
application  of  it  to  his  filter.  Neither  is  upward  filtration  new,  as 
already  stated ;  but  the  combination  of  the  two  and  in  this  particular 
form  will,  I  believe  commend  itself  to  any  one  who  will  give  it  a  trial. 
The  dimensions  given  furnish  a  filter  of  about  3  gallons  capacity  at 
a  cost  of  some  ten  or  twelve  shillings. — Fhar.  Jour,  and  Trans.,  May 
It),  1883. 
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