THE  GUMS  AND  RESINS  OF  COMMERCE. 
73 
Every  one  who  brings  the  result  of  his  researches  and  investi- 
gations to  bear  into  the  common  stock,  if  he  has  been  diligent 
and  treated  the  subject  fully  and  fairly,  must  contribute  some 
few  hints  that  may  prove  useful,  and  if  I  but  succeed  in  doing 
this,  I  shall  be  satisfied. 
I  must  premise  that  in  order  to  assimilate  my  information  to 
the  erroneous  nomenclature  of  city  circles  and  commercial  lists, 
I  am  obliged  to  depart  to  some  extent  from  the  true  scientific 
definition,  and  shall  speak  frequently  of  many  substances  as 
"gums,"  which  are  properly  gum  resins,  or  pure  resins.  Were 
I  not  to  do  this,  I  should  confuse  many  of  those  whom  I  see 
around  me,  and  who  have  had  to  buy  and  sell  by  names  which 
were  erroneously  given  years  ago,  before  chemical  analysis  had 
determined  the  true  composition  of  many. 
It  has  been  well  observed  by  Professor  Solly  (Jury  Reports, 
p.  71),  that  "  a  great  deal  of  practical  inconvenience  and  con- 
fusion is  caused  by  the  indiscriminate  manner  in  which  the  term 
gum  is  used  in  commerce  and  the  arts.  It  would  certainly  be 
an  advantage  if  the  distinctions  employed  in  scientific  books, 
were  to  be  generally  adopted  by  merchants  and  drug-brokers, 
the  term  gum  being  solely  applied  to  those  natural  vegetable 
exudations  which  soften  or  dissolve  in  water,  and  yield  a  more 
or  less  perfect  mucilage,  but  which  are  wholly  insoluble  in  spirit ; 
the  term  resin  being  applied  to  those  fusible  and  combustible 
vegetable  substances  which  are  quite  insoluble  in  water,  but  which 
soften  and  dissolve  in  ether,  the  "  essential  oils,"  and  "  spirits 
of  wine,"  and  the  term  gum  resin  being  used  to  designate  those 
mixtures  of  gum  and  resin  which  are  intermediate  in  properties, 
and  partake  of  the  nature  of  each,  being  partially  and  imper- 
fectly soluble  both  in  water  and  in  alcohol." 
Gum,  properly  so  called,  is  used  in  large  quantities  for  a  num- 
ber of  purposes  in  the  arts.  It  is  generally  distinguished  into 
soluble  gum,  or  gum  Arabic,  which  readily  and  perfectly  dissolves 
in  water,  forming  a  clear  mucilage,  and  cherry-tree  gum,  or  gum 
tragacanth,  and  those  difficultly-soluble  kinds  of  gum,  which, 
though  they  soften  easily,  do  not  readily  form  mucilage.  Gum 
is  extensively  used  in  finishing  and  giving  lustre  to  crapes,  silk 
goods,  &c,  by  calico  printers,  shoemakers,  and  in  other  trades. 
As  instances  of  the  immense  traffic  carried  on  in  gums,  I  may 
