^'"'■(iTJn^''^'}  Contributions  fro?n  the  School  of  Pharmacy,  etc,  457 
add  the  gutta  percha  to  the  chloroform,  in  a  bottle  provided  with  a 
finely-ground  stopper  and  designed  to  contain  the  preparation,  and  shake 
until  dissolved. 
Precautions.  If  all  the  vessels  are  not  clean  and  perfectly  free  from 
dust,  the  preparation  will  be  cloudy  ;  and  if  the  alcohol  be  not  wholly 
removed  from  the  precipitate,  the  preparation  will  be  milky.  In  the 
latter  case,  heating  causes  the  milkiness  to  disappear,  but  it  returns  on 
cooling  again.  If  milky  from  presence  of  alcohol,  the  liquor  can  be 
obtained  clear  by  evaporating  off  the  solvent  and  drying  in  a  thin  sheet  ; 
then  dissolving  in  chloroform  again. 
Ordinary  commercial  bisulphide  of  carbon  and  the  purified  chloro- 
form of  the  trade,  are  sufficiently  pure.  If  benzole  be  chosen  for 
purification,  it  should  be  0*85  sp.  gr.,  and  boiling  at  176°  or  178°  F. 
The  only  necessary  apparatus  not  found  in  all  drug  stores  consists  of 
the  bell-jar  with  ground  rim  and  plate,  the  burette,  the  retort  and 
receiver,  and  (?)  the  water-bath. 
Thin  sheets  of  gutta  percha  may  be  prepared  by  pouring  sufficient  of  the 
solution  into  a  breaker,  rolling  the  beaker  to  form  a  uniform  coating 
by  evaporation  of  the  solvent,  then  immersing  the  vessel  in  cold  water, 
when  the  film  may  readily  be  detached  from  the  glass. 
II.  Chemical  and  Microscopical  Examination  of  Cotton  Root 
Bark.    By  William  C.  Staehle,  P.  C. 
The  sample  examined  corresponded  petfectly  with  the  botanical 
description  recently  given  by  Professor  Maisch,*  with  the  additional 
particular  that  numerous  dark  spots  are  visible  to  the  unaided  eye  along 
the  inner  layer.  The  bark  was  more  or  less  quilled.  Its  powder  had 
an  ochre  color.    It  was  determined  to  be  from  G.  Herbaceum. 
It  also  agreed  with  the  following  microscopical  description  of  the  root 
bark  of  southern  cultivated  cotton  by  Professor  Harrington,  of  this 
University. f 
"  The  bark  consists  of  the  three  usual  layers.  The  outer  or  cortical 
layer  consists  of  several  rows  of  thin  walled,  tabular,  tangential  cells, 
with  some  granules  of  brown  matter  within.  The  middle  layer  is 
nearly  or  quite  interrupted  by  the  wedges  of  the  liber.  With  the 
medullary  rays,  it  consists  of  a  series  of  wedges,  with  their  bases  on 
*"Am.  Jour.  Phar.,"  1875,  p.  11,  (Jan.) 
f  From  MS.  of  "Identification  of  Vegetable  Drugs,  Foods  and  Fibres.'' 
