224 
REMARKS  ON  GUM  MESQUITE. 
I.  II. 
Carbon.       .        .       43.63  43.10 
Hydrogen     .       .         6.11  6.50 
Oxygen        .       .       47.26  47.40 
Ash            .       .         3.00  3.00 
100.00  100.00 
These  proportions  approximate  very  closely  to  those  obtained  from 
gum  Senegal  and  Arabic,  by  Guerin  and  Mulder.  The  general  appear- 
ance too  of  the  gum  is  similar  to  that  of  gum  Senegal  and  the  dark  in- 
ferior qualities  of  gum  Arabic.  In  chemical  properties  also  it  is  allied 
to  them,  being  insoluble  in  absolute  alcohol,  partially  soluble  in  common 
alcohol,  and  readily  forming  with  hot  or  cold  water  a  very  adhesive 
mucilage.  It  is,  in  fine,  a  true  gum,  and  promises,  in  its  physical  and 
chemical  behaviour,  much  of  the  advantage  expected  by  its  discoverer  as 
an  economical  substitute  for  gum  Arabic  or  Senegal. 
University  of  Maryland,  Baltimore,  January  10,  1855." 
By  a  comparison  of  some  of  these  statements  with  those  pub- 
lished by  us  as  above,  it  will  be  seen  that  several  discrepancies 
exist.    Dr.  Morfit  gives  the  specific  gravity  at  1.5,  whilst  that 
obtained  by  us  of  a  solid  lump  (by  carefully  weighing  in  oil  of 
turpentine  of  ascertained  density,  and  reducing  the  numbers  by 
calculation,)  was  1.311,  very  nearly  that  of  gum  Arabic.  In 
every  instance,  and  we  examined  several  of  the  pieces,  we  found 
them  entirely  soluble,  except  extraneous  matter,  (bark  and  other 
impurities)  and  saw    no    evidence  of  bassorin,   (yet  as  this 
principle  maybe  considered  as  matter  in  transition  between  iignin 
and  arabin  it  may  easily  exist  in  some  specimens  and  not  in  others, 
as  is  the  case  with  the  acacia  gums.)    The  amount  of  ash  ou- 
tlined by  incineration  in  a  platina  crucible  was  but  2.1  per  cent., 
whilst  in  the  above  analysis  it  was  3  per  cent.    Dr.  Morfit's  con- 
clusion that  gum  mesquite  is  composed  chiefly  of  arabin,  is  the 
chief  point  in  his  paper  to  which  we  take  exception,  as  the  opin- 
ion does  not  appear  to  be  founded  on  any  direct  test,  except  in- 
solubility in  alcohol  and  capability  of  yielding  a  mucilaginous 
solution,  as  the  ultimate  analysis  of  the  whole  gum  will  hardly 
be  brought  as  positive  evidence  of  the  identity  of  the  soluble 
matter  of  gum  mesquite  and  gum  arabic.    The  most  striking 
points  of  difference  in  their  reactions  are — that  a  solution  of  gum 
mesquite  is  not  precipitated  by  subacetate  of  lead,  nor  a  dense 
solution  coagulated  by  borax,  and  on  these  grounds  the  chemical 
identity  of  the  soluble  matter  of  gum  mesquite  and  the  arabin 
of  gum  arabic  may  well  be  doubted. 
