Am.  .lour.  Pharm.j 
March.  1«S5.  J 
Manufacture  of  Acetone. 
149 
the  atmosphere  of  vapor,  onto  the  cooler  portions  below,  to  be  mixed  and  car- 
ried up  again  in  a  similar  order.  At  the  same  time  the  whole  atmosphere  of 
the  still  is  filled  with  dust  which  becomes  very  fine,  and  very  largely  multiplies 
the  surfaces  of  contact  with  the  vapor  for  decomposition,  whilst  the  vapors 
pass  slowly  and  uniformly  and  with  a  minimum  of  friction  to  the  exit  at  the 
condenser  end.  If  the  motion  and  heating  of  a  charge  in  this  still  be  compared 
with  those  in  a  stationary  still  with  a  horizontal  stirrer  driven  by  a  vertical 
shaft,  the  advantages  of  the  former  will  be  easily  understood.  The  latter 
moves  the  charge  round  over  the  fire,  but  has  a  comparatively  slight  effect  in 
bringing  new  portions  of  the  charge  successively  in  contact  with  the  heating 
surfaces,  and  it  does  not  tend  to  prevent  horizontal  stratification  of  the  charge 
with  consequent  irregular  heating  ;  and  it  does  not  tend  to  the  fullest  contact 
of  the  vapors  with  the  surfaces  of  the  charge,  where  the  decomposition  proba- 
bly takes  place.  After  the  inevitable  number  of  trials  and  adjustments  and 
breakings  down,  the  following  successful  experiments  are  selected  from  a 
large  number : 
(4)  As  a  parallel  experiment  to  (1)  with  the  stationary  still,  the  rotary  still 
was  used  empty. 
About  200  Cc.  of  36  p.  c.  acid  =  72  Gm.  of  absolute  acid  was  slowly  passed 
into  the  heated,  rotating,  empty  still. 
The  first  hot  flask  of  distillate  contained  33  Cc.  of  acid  of  14-6  p.  c.  =  4  82  of 
17  89  Gm.  absolute  acid. 
The  second  ice-bath  flask  contained  142  Cc.  of  acid  acetone,  12  6  p.  c. 
Gm.  absolute  acid.  Then  4-82  +  17  89  =  2271  Gm  absolute  acid  distilled  over 
unchanged.  Then  72  Gm. — 2271  =  49-29  Gm.  of  acid  decomposed.  The 
second  distillate  gave  an  estimate  of  12. 1  Gm.  acetone.  Then  as  49.29  acid  : 
12 'i  acetone:  :  100  :  24*5  p.  c.  acetone  from  the  acid.  The  current  of  inflam- 
mable gas  was  considerable,  but  less  than  in  (1). 
(5)  The  rotary  still  was  charged  with  about  a  litre  of  the  same  granulated 
pumice  used  in  (2),  and  when  heated  about  295  Cc.  of  60  p.  c.  acid  =  177  Gm. 
of  absolute  acid,  was  passed  in  in  vapor  during  3*5  hours. 
The  first  distillate,  hot  flask,  had  108  Cc.  of  acid  water  of  4*4  p.  c.  =475 
Gm.  acid. 
The  second  distillate,  ice-bath  flask,  had  116  Cc.  acid  acetone  2*4  p.c. 
acid  =  278  Gm.  acid. 
Then  475 +  278  =  7*53  Gm.  acid  came  over  unchanged,  out  of  177  Gm. 
passed  in  ;  or,  177  —  7*53  =  169-47  Gm.  decomposed. 
The  acetone  estimated  by  iodoform  was  24-3  p.  c.  of  the  acid  decomposed. 
(6)  About  500  Gm.  of  precipitated  barium  carbonate  was  put  into  the  rotary 
still  on  top  of  the  charge  of  pumice,  and  when  the  whole  was  heated  380  Cc. 
60  p.  c.  acid  =  228  Gm.  of  absolute  acid  was  passed  in  in  vapor  during  3-5 
hours. 
The  first  distillate  was  108  Cc.  of  acid  water  containing  3-9  Gm.  acid. 
The  second  distillate  was  135  Cc.  of  acid  acetone  containing  2  7  Gm.  acid. 
228  Gm.  acid —  6'6  Gm.  over  unchanged  =  221-4  Gm.  decomposed. 
The  estimated  acetor  e  was  16  p.  c.  of  the  acid  decomposed. 
Much  inflammable  gas  throughout  the  process. 
(7)  About  456  Gm.  of  precipitated  barium  carbonate  put  into  the  cleaned-out 
rotary  still,  and  when  heated  510  Cc.  of  36  p.c.  acid  =  183*6  Gm.  absolute  acid 
