166 
Oil  of  Pennyroyal. 
f  Am.  Jour.  Pharm. 
I       April.  1888. 
V.  To  a  small  quantity  of  the  barium  solution  very  dilute  sulphuric 
acid  was  added  as  long  as  a  precipitate  was  produced,  filtered,  distilled 
and  treated  with  magnesium  oxide  (See  method  of  Dr.  A.  Meyer, 
Chemische  Analyse^  page  55),  which  on  evaporation  remained  some- 
what sticky  while  warm. 
VI.  0*216  gms.  of  the  barium  salt  were  dissolved  in  water;  very 
dilute  sulphuric  acid  was  added  as  long  as  a  precipitate  formed ;  the 
liquid  was  filtered,  the  precipitate  dried  and  weighed,  giving  0.220 
gms.  of  barium  sulphate.  The  percentage  of  barium  present  was  cal- 
culated as  follows:  232-8  :  136-8 :  :  -220:  '1292; 
Then  -216:  -1292:: -100:  59-85. 
Calculated : 
Ba  (CaHgO^)^.  Ba  (CHO^)^.  Found. 
Ba==53-68%.  Ba=60-52%.  Ba=59'85%. 
VII.  The  acid  set  free  in  the  foregoing  reaction  was  treated  with 
excess  of  freshly  precipitated  carbonate  of  lead,  filtered,  evaporated  and 
treated  with  alcohol  and  filtered ;  only  a  small  amount  was  found  to 
have  been  dissolved,  an  aqueous  solution  of  which  gave  with  mercuric 
chloride  no  precipitate,  but,  with  ferric  chloride  a  bright-red  color 
showing  the  absence  of  formic  and  the  presence  of  acetic  acid.  The 
portion  insoluble  in  alcohol  was  dissolved  in  water,  and  gave  a  white 
precipitate  with  solution  of  silver  nitrate,  reduced  on  heating.  Thus 
it  will  be  seen  that  reactions  V.,  VI.  and  VII.  shoAv  the  presence  of 
a  small  quantity  of  acetic  acid.  gave  the  same  reactions  for  formic 
and  acetic  acids  as  X. 
Crystals  found  in  the  broken  flask. — The  flask  was  first  rinsed  with 
petroleum  spirit  and  allowed  to  evaporate,  but  no  crystals  were  ob- 
served. The  flask  was  then  rinsed  with  ether,  and  evaporated,  show- 
ing a  number  of  small  needle-shaped  crystals  on  the  side  of  the 
beaker;  on  heating  a  few  of  these  they  were  found  to  be  easily  volatil- 
ized. The  flask  was  rinsed  with  more  ether,  which  was  added  to  the 
crystals,  to  evaporate  over  night,  with  a  view  of  obtaining  a  larger 
quantity,  but  unfortunately  the  ether  drove  the  crystals  up  the  sides  of 
the  beaker,  into  the  filtering  paper  used  as  a  cover,  and  so  were  lost» 
Experiments  with  hydrochloric  acid. — I.  Portions  of  different  frac- 
tions of  the  oil  were  placed  in  a  freezing  mixture  and  dry  hydrochloric 
gas  passed  in  until  saturated.  They  at  first  acquired  a  dark  color, 
which  on  standing  gradually  became  lighter,  but  nothing  separated  out. 
