588  •  Pressure  Attachment  for  Desiccators.  {Ag^four-  phann- 
•ember,  190^. 
A  PRESSURE  EQUALIZING  ATTACHMENT  FOR 
DESICCATORS. 
By  Edwin  Dowzard. 
Everyone  has  noticed  the  jump  and  side-slip  of  desiccator  lids 
after  placing  hot  crucibles  or  basins  therein.  This  is  of  course 
caused  by  the  expansion  of  the  contained  air,  brought  about  by  the 
hot  article.  When  the  contents  of  the  desiccator  have  cooled  there 
is  a  slight  vacuum  which  renders  the  lid  somewhat  difficult  to 
remove ;  when  the  lid  has  been  removed  there  is  a  sudden  inrush  of 
A.  CaCl2  tube  charged  with  CaCl2.    B.  Tube  connecting  U-tube  with  outside  air. 
air  which  does  not  improve  the  efficiency  of  the  desiccator.  These 
faults  may  be  remedied  in  a  very  simple  manner  by  the  attachment 
illustrated  in  the  sketch.  The  apparatus  consists  of  a  calcium 
chloride  U-tube  to  which  has  been  fused  a  piece  of  glass  tubing  bent 
to  fit  against  the  inside  surface  of  the  desiccator.  The  end  of  the 
tube  passes  through  a  perforated  rubber  stopper  fitted  in  the  neck. 
It  will  be  seen  that  the  U-tube  charged  with  calcium  chloride  allows 
the  expanded  air  to  escape  and  also  allows  dry  air  to  enter,  thus 
keeping  the  air  inside  the  desiccator  at  the  same  pressure  as  the 
surrounding  atmosphere. 
This  apparatus  has  been  in  use  for  several  years,  giving  perfect 
satisfaction. 
Analytical  Department,  Parke,  Davis  &  Co.,  Detroit. 
