510  British  Pharmaceutical  Confere7ice.  { 
Am.  Jour.  Pharni. 
Oct.,  1891. 
the  ash  from  genuine  gum  arabic,  confirm  previous  statements  that  the  muci- 
lage formed  from  it  is  decidedly  more  viscid  than  that  from  ordinary  gum, 
arabic.  The  " absolute  viscosity,"  as  determined  by  a  specially  constructed 
apparatus,  ranged  from  10  per  cent,  solutions  of  gum  arabic  from  "0639  to  '1850  ; 
whilst  10  per  cent,  mucilages  of  "ghatti  "  ranged  from  -2880  to  "3621  and  5  per 
cent,  from  "1350  to  '1760.  The  authors  are  of  opinion  therefore  that  to  pro- 
duce from  average  ghatti  gum  a  mucilage  corresponding  in  viscosity  to  the 
B.P.  mucilage  of  acacia  it  would  be  necessary  to  use  not  less  than  8  parts  of 
water  to  1  part  of  gum.  The  reagents  best  suited  for  the  detection  of  ghatti 
gum  were  stated  to  be  ammonium  oxalate,  which  produces  in  the  mucilage 
only  a  slight  turbidity  as  compared  with  the  copious  white  precipitate  thrown 
down  from  gum  arabic  ;  ferric  chloride,  which  causes  a  slight  darkening  and  a 
gelatinous  precipitate  ;  alcohol,  which  throws  down  only  a  slight  precipitate  ; 
and  mercuric  chloride,  which  produces  a  white,  stringy  precipitate,  whilst  with 
gum  arabic  it  gives  no  perceptible  reaction.  Ghatti  mucilage  is  described  by 
the  authors  as  yellowish  or  light  brown  in  color  when  properly  made,  and  as 
being  much  more  permanent  and  retaining  its  viscosity  unimpaired  for  a  longer 
time  than  mucilages  of  inferior  gum  arabics  from  Senegal  and  Barbary.  As  is 
"known,  commercial  samples  of  ghatti  gum  are  generally  dirty  and  mixed  with 
fragments  of  bark,  the  tannin  from  which,  if  it  goes  into  solution,  spoils  the 
color  of  the  mucilage  and  causes  a  further  darkening  in  contact  with  iron  salts. 
In  order  to  avoid  this  objection  it  is  recommended  that  the  gum  be  powdered 
in  porcelain  or  stone  ware,  the  powder  treated  with  half  the  quantity  of  cold 
water  required  for  the  finished  mucilage,  the  whole  well  stirred  until  the 
swollen  metarabin  has  separated  from  the  soluble  gum,  then  strained  through 
muslin,  and  the  swollen  pieces  of  insoluble  gum  picked  out  and  submitted  to 
similar  treatment  with  the  remainder  of  the  water.  In  this  way  a  strong 
mucilage  can  be  obtained  before  the  cold  water  has  had  time  to  dissolve  out  the 
tannin  from  the  debris  to  any  appreciable  extent.  In  the  authors'  opinion 
mucilage  made  in  accordance  with  these  directions  is  quite  capable  of  replacing 
gum  acacia  for  pharmaceutical  work.  In  the  discussion  of  the  paper,  however, 
this  position  was  disputed  by  several  speakers  ;  at  the  same  time  it  was  admitted 
that  for  many  technical  purposes  gum  ghatti  forms  a  useful  substitute  for  gum 
acacia. 
The  Conference  then  adjourned  for  luncheon,  and  on  resuming  a  paper  was 
read  on  the  Estimation  of  Volatile  Oil  in  Copaiba,  in  which  Mr.  Cripps 
described  an  apparatus  he  had  devised  for  the  purpose.  In  this  the  copaiba  is 
submitted  to  the  action  of  a  current  of  steam,  which  rapidly  removes  the  vola- 
tile oil  and  leaves  the  resin  in  an  unaltered  condition.  Incidentally  it  was 
mentioned  that  in  eleven  commercial  samples  of  copaiba  quantities  of  volatile 
oil  varying  from  40-95  to  59 -6  per  cent,  had  been  found,  and  that  turpentine 
appears  to  be  now  seldom  employed  to  adulterate  copaiba. 
The  occurrence  in  commerce  in  recent  years  of  a  Liquid  Persian  Galbanum, 
in  the  form  of  a  reddish-brown  liquid  of  the  consistence  of  Venice  turpentine, 
has  led  Mr.  K.  M.  Holmes  to  attempt  to  clear  up  the  local  and  botanical  origin 
of  the  different  varieties  of  galbanum,  and  his  conclusions  were  given  in  the 
paper  next  read.  Galbanum  is  usually  spoken  of  either  as  "  Levant  "  or  "  Per- 
sian," the  sorts  termed  "  Persian  "  diffeang  from  the  "  Levant  "  in  the  posses- 
sion of  a  turpentiny  odor  in  addition  to  that  of  galbanum.    Mr.  Holmes  is  of 
