mrch^mT'}     Preparation  of  Absolute  Alcohol  111 
As  far  as  my  experience  extends,  the  article  which  last  winter  (1870- 
71)  was  in  the  American  market  under  the  name  of  African  saffron, 
was  carthamus,  while  about  the  same  time  a  small  lot  of  (probably) 
scrophulariaceous  flowers  were  offered  in  the  London  market  under 
the  same  name. — Proceedings  of  the  Amer.  Pharm.  Assoc.,  1877. 
PREPARATION  OF  ABSOLUTE  ALCOHOL. 
By  E.  Erlenmeyer. 
The  processes  mostly  in  use  for  the  preparation  of  larger  quantities 
of  absolute  alcohol  are  very  tedious,  because  the  dehydrating  agents, 
like  carbonate  of  potassa,  anhydrous  sulphate  of  copper,  anhydrous 
ferrocyanide  of  potassium,  burned  lime,  caustic  baryta,  &c,  combine 
with  the  water  only  after  prolonged  contact.  The  three  first-named 
substances  do  not  yield  perfectly  absolute  alcohol  even  after  several 
days'  contact  and  frequent  agitation. 
Mendelejeff,*  in  his  valuable  researches  on  the  combinations  of 
alcohol  with  water,  has  carefully  investigated  the  various  agents  for 
the  production  of  absolute  alcohol,  and  prefers  caustic  lime  to  all 
others.  He  employs  alcohol  having  a  specific  gravity  not  higher  than 
0-792,  at  20°  C,  and  pieces  of  burned  lime  projecting  above  the  sur- 
face, when  the  alcohol  will  be  dehydrated  in  two  days ;  but,  if  the 
distillation  is  desirable  after  2  or  8  hours,  he  directs  the  two  articles 
to  be  previously  heated,  for  half  an  hour,  to  50  or  60°  C.  With  this 
manipulation,  however,  only  the  middle  portions  of  the  distillate  are 
obtained  anhydrous. 
I  have  altered  Mendelejeff's  directions,  so  as  to  boil  upon  the  water 
bath,  for  one-half  to  one  hour,  in  a  still  connected  with  a  return 
cooler;  afterwards  the  cooler  is  reversed  and  the  alcohol  distilled, 
when  the  entire  distillate  is  obtained  in  the  anhydrous  condition.  If 
the  alcohol  contains  over  5  per  cent,  of  water,  it  is  merely  requisite 
to  subject  it  twice  or  three  times  to  the  same  treatment.  Should  it 
contain  much  water,  then  the  lime  must  not,  on  the  first  boiling,  pro- 
ject above  the  surface  of  the  alcohol.  It  is  better  to  fill  only  half  of 
the  space  occupied  by  the  latter,  with  pieces  of  lime,  otherwise  its 
rapid  hydration  endangers  the  safety  of  the  still.  Several  litres  of 
spirit  may  by  this  method  be  converted  into  absolute  alcohol  within  a 
few  hours. — Annal.  der  Chem.  und  Pharm.,  1871,  Nov.,  249. 
*  Zeitschr.  f.  Chemie,  1865,  260. 
