Am.  Jour.  Pharm.  ) 
Sept.,  1880.  / 
Spurious  Gums. 
451 
residue,  dried  at  qo^C.  till  constant  and  its  weight  taken;  from  this  is 
calculated  total  percentage  of  gum. 
An  accurately  weighed  portion  of  the  dried  gum  was  treated  with 
water  until  nothing  further  dissolved,  the  residue  collected  in  a  tared 
filter,  dried  at  ioo°C.  and  weighed.  This  weight,  less  that  of  filter, 
gives  weight  of  gum  insoluble  in  water;  this  deducted  from  that  of 
total  gum  gives  by  difference  gum  soluble  in  water. 
Determination  of  Resin^  etc. — The  weight  of  this  is  taken  by  dif- 
ference," and  includes  resins,  volatile  oil,  if  any,  and  other  substances 
soluble  in  absolute  alcohol. 
I.  Opaque  Bdellium  [Balsamodendron  Playfairii)  is  a  very  hard,  yellow 
ochre-colored,  opaque  gum-resin,  with  but  slight  odor  and  a  bitter  taste. 
In  common  with  other  exudations  from  the  genera  Balsamodendron  and 
Boswellia^  tears  of  this  substance  frequently  have  portions  of  papery 
bark  attached  to  their  surface.  Triturated  with  water,  opaque  bdellium 
forms  a  very  good  cream-colored  emulsion.  Cold  absolute  alcohol 
dissolves  about  50  per  cent.  ;  the  residue  is  not  entirely  soluble  in 
water,  the  insoluble  portion  swelling  up  and  giving  the  characters  of 
bassorin. 
The  coloring  matter  appears  to  be  due  to  a  resin  very  soluble  in 
alcohol,  giving  a  canary  yellow  colored  tinctures;  this  resin  is  also 
soluble  in  ether,  benzol  and  chloroform.  The  tincture  (i  of  gum-resin 
to  6  of  rectified  spirit)  becomes  slightly  milky  with  alcoholic  solution 
of  plumbic  acetate,  gives  a  slight  yellow  precipitate  with  one  drop  of 
liq.  plumbi  subacet.,  and  ^an  intense  greenish-black  color  with  tinct. 
ferri  perchlor.^    The  tincture  is  bitter  and  becomes  milky  with  water. 
The  mucilage  made  by  dissolving  i  part  of  the  gum  (completely 
washed  with  rectified  spirit)  in  40  of  water  is  tasteless,  partly  precipi- 
tated by  subacetate  of  lead  and  not  at  all  by  neutral  acetate. 
The  ash  (i'6jper  cent.)  appears  to  be  chiefly  calcic  carbonate,  dis- 
solving entirely  with  effervescence  in  dilute  acetic  acid  and  giving  a 
copious  precipitate  with  ammonium  oxalate. 
Water  distilled  from  opaque  bdellium  had  the  slight  odor  of  the 
drug,  but  there  was  no  appearance  of  oil  globules  in  working  on  a 
small  scale. 
1  Ferric  chloride  does  not  give  this  reaction  with  a  tincture  of  "  gunn  hodthai"  or 
*'gum  hotai,"  a  substance  which  has  been  referred  to  the  same  botanical  source  as 
opaque  bdellium. 
