444 
DOUBLE  SALTS  OF  CARBOLIC  ACID. 
with  most  inadequate  means  and  much  discouragement  to  the 
laborers,  the  amount  obtained  is  very  great. 
If  we  take  into  account  the  similarity  of  the  recent  and  fossil 
resins  in  appearance,  their  near  approach  in  physical  properties, 
the  fact  that  the  recent  gum,  often  being  imbedded  in  sand, 
takes  the  characteristic  surface-markings,  and  recollect  that 
where  now  the  good  Copal  is  dug  as  a  fossil  the  present  Copal- 
tree,  in  all  probabilty,  once  grew,  when  the  sea  was  nearer  to 
the  hills  than  now, — I  think  we  may  be  satisfied  that  the  Tra- 
chylohium  was  the  source  of  the  old  Copal,  which  is  the  resin 
only  modified  by  time  and  long  exclusion  from  air  and  light 
under  the  ground. 
Perhaps  it  may  be  asked,  is  there  not  proof  in  the  gum  itself 
that  the  Trachylohium  then  existed  ?  I  have  as  yet  .found  none  : 
insects  (all  of  them  serial)  are  oTten  preserved ;  sometimes 
branches  and  leaves ;  but  I  have  not  seen  evidence  of  the  Copal- 
tree.  When  we  remember  that  the  resin  soon  hardens  after 
being  exuded,  and  that  it  runs  from  the  underside  of  the  main 
limbs,  while  the  leaves,  flowers  and  fruit  are  at  the  extremities 
of  the  branches,  we  shall  see  that  leaves  of  the  underwood  which 
sweep  the  lower  branches  are  much  more  likely  to  be  embalmed 
than  the  leaf  of  the  tree  itself,  which,  besides,  is  hairy,  glossy, 
and  unlikely  to  adhere.  If  a  part  of  the  modern  tree  were 
found  in  the  old  hard  gum,  the  proof  would  be  complete  ;  at 
present  some  doubt  remains. 
I  have  sent  not  only  full  herbarium  specimens,  but  also  speci- 
mens of  the  recent  gum,  of  the  "  Chakazzi,''  and  of  the  valua- 
ble Copal,  in  which  are  many  insects ;  and  I  would  suggest  that 
entomologists  should  assist  us  by  their  opinions  whether  these 
belong  to  existing  species  or  not. — Pharyn.  Journ.,  May,  1869, 
from  the  Journal  of  the  Linnean  Society. 
DOUBLE  SALTS  OF  CARBOLIC  ACID. 
At  the  Royal  Medical  and  Chirurgical  Society  a  paper,  by 
Dr.  Arthur  Ernest  Sansom,  on  these  new  salts  was  read. 
Modern  research  has  established,  with  a  near  approach  to  pre- 
cision, the  doctrine  that  zymotic  diseases  are  due  to  the  influence 
