4io  Spurious  Gums.  ^7..^^^"" 
the  results  of  a  somewhat  more  detailed  examination  of  the  impurities 
there  referred  to. 
It  will,  of  course,  be  understood  that  these  substances  rarely  find 
their  way  into  the  best  parcels  of  "picked  Turkey  myrrh,"  being  care- 
fully rejected  by  the  wholesale  houses. 
Five  substances  will  be  referred  to,  those  met  with  in  largest  quan- 
tity, viz. : 
1.  Opaque  bdellium. 
2.  African  bdellium. 
3.  Opaque  tasteless  gum-resin. 
4.  Yellow  tasteless  gum-resin. 
5.  Bitter  acrid  gum. 
The  percentage  composition  of  these  impurities  as  given  in  this  note 
is  based  upon  the  solubility  of  the  substance  in  absolute  alcohol  and 
water,  and  will  serve  to  give  an  idea  of  their  constitution,  but  the 
results  do  not,  of  course,  indicate  the  exact  proximate  constituents. 
The  general  outline  of  the  analysis  is  as  follows  : 
Several  of  the  largest  and  most  characteristic  of  the  tears  were 
selected,  the  outer  portions  removed,  so  as  to  leave  the  "gum"  quite 
free  from  extraneous  impurity  and,  if  sufficiently  hard,  reduced  to  a 
fine  powder,  otherwise,  as  in  the  case  of  "bitter  acrid  gum,"  cut  into 
thin  shavings  with  a  knife. 
Determination  of  Moisture  and  Ash. — About  l  gram  of  the  powder, 
accurately  weighed  in  a  platinum  dish,  was  exposed  in  a  hot-air  bath  at 
ioo°C.  for  several  hours  until  it  ceased  to  lose  weight.  The  loss  of 
weight  =  moisture.  A  little  volatile  oil  might  be  dissipated  in  this 
process,  but  it  is  probable  that  a  dry  heat  of  ioo°C.  would  not  cause 
much  error  from  that  cause.  The  dry  residue  was  then  ignited  until 
all  traces  of  carbon  were  removed.  The  weight  of  dish  and  ash  less 
that  of  dish  (weighed  after  ignition)  indicates  "the  ash."  The  "ash" 
is  not  included  as  a  separate  item  in  the  percentage  composition,  because 
all  extraneous  matter  had  been  removed  \  it  would,  therefore,  have 
been  in  a  state  of  combination  with  the  gum,  and  would  be  included 
in  the  weight  of  that  constituent. 
Determination  of  Gum. — 2  or  3  grams  of  the  powder  were  digested 
with  successive  portions  of  absolute  alcohol  and  the  tincture  decanted; 
when  the  soluble  portion  was  nearly  all  removed,  the  residue  was  col- 
lected in  a  weighed  filter,  washed  till  the  evaporated  filtrate  left  no 
