82 
PROPIONIC  AND  BUTYRIC  ACIDS,  ETC. 
who  are  ignorant  of  such  scenes  as  we  have  described  will  not  he 
disappointed  in  reading  the  history  of  our  visit ;  while  those  who 
live  in  districts  like  ourselves,  can,  from  similar  experience,  follow 
us  in  every  line  of  our  rambles. 
A.  W.  Smith. 
Rye,  Sussex,  Oct.  25,  1866. 
— London  Chemist  and  Druggist,  Nov.  15,  1866. 
ON  THE  PRESENCE  OF  PROPIONIC  AND  BUTYRIC  ACIDS 
AMONG  THE  PRODUCTS  OF  THE  DESTRUCTIVE  DIS- 
TILLATION OF  WOOD. 
By  Thomas  Anderson,  M.  D.,  F.  R.  S.  E.,  Professor  of  Chemistry  in 
the  University  of  Glasgow. 
In  the  manufacture  of  sodic  acetate  from  crude  pyroligneous 
acid,  a  mother  liquor  is  obtained,  which,  even  when  highly  con- 
centrated, refuses  to  yield  a  further  crop  of  crystals.  On  the 
addition  of  sulphuric  acid,  Jiowever,  it  is  found  still  to  contain 
abundance  of  acetic  acid,  having  a  peculiar  rancid  smell,  which 
led  me  to  suspect  the  presence  of  some  of  its  homologues. 
In  order  to  ascertain  whether  this  was  the  case,  a  considerable 
quantity  of  the  mother  liquor  in  question  was  supersaturated 
with  sulphuric  acid,  and  allowed  to  stand.  The  crystals  of 
sodic  sulphate  which  deposited  having  been  separated,  the  fluid 
was  cautiously  distilled  on  a  sand-bath,  care  being  taken  to  stop 
the  process  as  soon  as  the  slightest  trace  of  sulphurous  acid  was 
observed.  The  distillate  was  saturated  with  sodic  carbonate, 
and  on  evaporation  yielded  an  abundant  crop  of  crystals  of  sodic 
acetate.  These  having  been  separated,  the  mother  liquor  was 
again  concentrated,  and  this  was  repeated  as  long  as  crystals 
were  obtained.  A  thick  oily  fluid  was  left,  to  which  concen- 
trated sulphuric  acid  was  added  in  large  excess,  and  the  layer 
which  rose  to  the  surface  was  separated  and  distilled. 
The  greater  part  of  it  passed  over  between  117°  and  120° 
C,  and  obviously  consisted  of  pure  acetic  acid;  but  after  it  had 
distilled,  the  thermometer  gradually  rose,  and  small  fractions 
were  collected  until  it  reached  200°,  at  which  point  only  a  small 
quantity  of  fluid  remained  in  the  retort. 
The  fraction  distilling  between  138°  and  143°  was  converted 
