258         Simple  Forms  of  Laboratory  Apparatus.    { *m  jinYifra*™1 
because  of  its  greater  gravity ;  so  that  it  is  obvious  that  greater 
activity  with  use  of  less  acid  is  obtainable. 
By  using  hydrochloric  acid  in  the  bottle  and  marble  in  the  lamp 
chimney,  the  apparatus  can  be  used  for  the  generation  of  carbon 
dioxide. 
An  apparatus  giving  very  good  results  in  the  estimation  of  car- 
Apparatus  for  Generating  Hydrogen  Sulphide  or  Carbon  Dioxide. 
bonates  can  be  easily  constructed  from  2-ounce  Erlenmeyer  fla.-k>, 
small  calcium  chloride  tubes  (the  smaller  ends  of  which  have  been 
closed  by  fusion),  rubber  corks,  5  c.c.  test-tubes  and  small  glass 
tubing  drawn  out  into  capillary  tubes  below  the  corks  (to  decrease 
the  weight  of  the  apparatus  and  to  reduce  the  size  of  the  bubbles  of 
gas  or  air  in  passing  through  sulphuric  acid). 
