ON  THE  SOLUBILITY  OE  MEDICINAL  PRINCIPLES. 
45 
when  so  obtained,  the  ether  may  be  replaced  by  alcohol  and  all 
that  is  medicinal  held  in  solution  by  that  grand  solvent. 
But  while  alcohol  is  the  specific  solvent  of  all  the  medicinal 
elements  of  vegetation,  they  are  most  of  them  while  in  their 
native  combinations  soluble  in  water  also ;  this  is  the  most  uni- 
versal solvent  in  nature.    This  alone  will  probably  extract  all 
the  virtues  of  jalap  and  podophyllum  and  leave  little  but  the  in- 
ert vegetable  fibre.    For  the  resinous  principles  of  these  roots, 
in  their  natural  state,  are  held  in  such  intimate  combination  with 
the  other  elements  that  they  are  dissolved  out  and  held  in  solu- 
tion with  them.    Thus  the  watery  extracts  of  such  roots  actually 
contain  their  medicinal  virtues  although  greatly  diluted  with 
other  non-medicinal  principles.    But,  if  that  native  combination 
is  once  broken  up  or  disturbed,  those  resinous  principles  separate 
and  are  not  again  soluble  in  that  menstruum.    When  obtained, 
however,  by  this  or  other  injudicious  processes,  these  resinoid 
principles  and  perhaps  others  originally  medicinal,  are  liable  to 
become  so  changed  in  their  original  constitution  by  the  action  of 
heat,  water  and  oxygen,  as  to  be  no  longer  soluble  in  alcohol, 
and  just  so  far  as  this  is  the  case  their  medicinal  properties  are 
destroyed  and  they  become  inert.    Thus  the  medicinal  value  of 
jalapin,  podophyllin,  leptandrin  and  the  other  resinoids  may  be 
correctly  estimated  by  their  solubility  in  alcohol,  for  so  far  as 
they  are  thus  insoluble  they  are  worthless. 
Many  vegetables  which  we  habitually  use  as  wholesome  escu- 
lents, contain  some  elements  soluble  in  alcohol,  but  these  when 
separated  and  concentrated  will  be  found  to  be  active  medicines 
or  poison.  In  themselves  they  are  not  nutritious  but  medicinal, 
but  in  the  small  proportions  in  which  they  are  found  in  our  food, 
they  may,  like  the  pepper,  and  ginger  and  cayenne,  and  common 
salt,  which  we  use  as  condiments,  serve  as  healthful  stimulants 
to  the  digestive  organs,  and  thus  aid  in  the  assimilation  of  those 
substances  which  are  really  nutritive. 
I  have  above  advocated  the  truth  of  this  hypothesis  as  applied 
to  vegetable  substances  only  ;  but  if  the  bone  phosphate  of  lime, 
(which  I  believe  is  not  soluble  in  alcohol),  is  entirely  inert,  as 
is  the  opinion  of  Prof.  Wood,  then  I  know  of  no  exception  to 
its  application  to  the  whole  animal  kingdom  also. 
I  wish  it  to  be  understood,  however,  that  I  contend  for  the 
